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Photographic 

Sciences 
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Microfiche 

Series. 


CIHM/ICMH 
Collection  de 
microfiches. 


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Technical  and  Bibliographic  Notes/Notes  techniques  et  bibliographiques 


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Coiou'ed  pages/ 
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Pages  endommag^es 


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n 


n 


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II  se  peut  que  certaines  pages  blanches  ajoutAes 
lors  d'une  restauration  apparaissent  dans  le  texte, 
mais,  lorsque  cela  6tait  possible,  ces  pages  n'ont 
pas  iti  filmies. 


n 


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The  copy  filmed  here  has  been  reproduced  thanks 
to  the  generosity  of: 

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University  of  New  Brunswick 


L'exemplaire  film6  fut  reproduit  grflce  d  la 
g6n6rosit6  de: 

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The  images  appearing  here  are  the  best  quality 
possible  considering  the  condition  and  legibility 
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Original  copies  in  printed  paper  covers  are  filmed 
beginning  with  the  front  cover  and  ending  on 
the  last  page  with  a  printed  or  illustrated  impres- 
sion, or  the  back  cover  when  appropriate.  All 
other  original  copies  are  filmed  beginning  on  the 
first  page  with  a  printed  or  illustrated  impres- 
sion, and  ending  on  the  last  page  with  a  printed 
or  illustrated  impression. 


The  last  recorded  frame  on  each  microfiche 
shall  contain  the  symbol  — ^  (meaning  "CON- 
TINUED"), or  the  symbol  V  (meaning  "END"), 
whichever  applies. 

Maps,  plates,  charts,  etc.,  may  be  filmed  at 
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beginning  in  the  upper  left  hand  corner,  left  to 
right  and  top  to  bottom,  as  many  frames  as 
required.  The  following  diagrams  illustrate  the 
method: 


Les  images  suivantes  ont  6t6  reproduites  avec  le 
plus  grand  soin,  compte  tenu  de  la  condition  et 
de  la  nettet6  de  l'exemplaire  film6,  et  en 
conformity  avec  les  conditions  du  contrat  de 
filmage. 

Les  exemplaires  originaux  dont  la  couverture  en 
papier  est  imprim6e  sont  film^s  en  commenpant 
par  le  premier  plat  et  en  terminant  soit  par  la 
dernidre  page  qui  comporte  une  empreinte 
d'impression  ou  d'illustration,  soit  par  le  second 
plat,  selon  le  cas.  Tous  les  autres  exemplaires 
originaux  sont  film6s  en  commen^ant  par  la 
premidre  page  qui  comporte  une  empreinte 
d'impression  ou  d'illustration  et  en  terminant  par 
la  dernidre  page  qui  comporte  une  telle 
empreinte. 

Un  des  symboles  suivants  apparaitra  sur  la 
dernidre  image  de  cheque  microfiche,  selon  le 
cas:  le  symbole  —^  signifie  "A  SUIVRE",  le 
symbole  V  signifie  "FIN  ". 

Les  cartes,  planches,  tableaux,  etc.,  peuvent  dtre 
film6s  d  des  taux  de  reduction  diff^rents. 
Lorsque  le  document  est  trop  grand  pour  dtre 
reproduit  en  un  seul  clichd,  il  est  film6  d  partir 
de  Tangle  supdrieur  gauche,  de  gauche  d  droite, 
et  de  haut  en  bas,  en  prenant  le  nombre 
d'images  ndcessaire.  Les  diagrammes  suivants 
illustrent  la  mdthode. 


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I] 


13.1 


THE    DESIGNING 


OF  ORDINARY 


IRON  HIGHWAY  BRIDGES, 


BY 


J.  A.  L.  WADDELL,  C.  E.,  B.A.Sc,  Ma.E., 

'^"'■'^r^i'lT'    ^'"^""'-'='''    "^'ANSAS    CITV,    MO.;    ALSO   ENGINEER    IN   CHARGE   OF   THE   WESTERN   0FP1CK 

OF  THE   IHOiNlX   BRIDGE  COMPANY  AND  THE   PHCENIX   IRON  COMPANY;    FORMERLY  PROFESSOH 

OF  CIV.I.   ENGINEERING   IN   THE   IMPERIAL   UNIVERSITY   OF   JAPAN       MEMlfER   OF  ^hI 

AMERICAN  SOCIETY  OF  CIVIL  ENGINEERS,  AMERICAN  SOCIETY  OF  MECHANIcIl 

ENGINEERS,  LA   SOClfiTlt  DES  INofeNIEURS  CIVILS,    PARIS,    RENSSELAER 

SOCIETY   OF   ENGINEERS,  ENGINEERS*  CLUB  OF   PHILADEI  PHIA 

WESTERN  SOCIETY  Or  KNGINEEHS.  AND  FNGINEERs'  CLUB       ' 

OF    KANSAS    l(.  ASSOCIATE     MEMlUiR    OFIHE 

INSTITUTION       F  CIVIL  ENGINEERS,  LONDON, 

AND    HONORARY    MEMBEk    OF    THE 

KOGAKU    KYOKAI     (JAPANESE 

ENGINEERING  SOCIETY). 


FJFTH  EDITION. 

SECOND   THOUSAND. 


NEW  YORK : 

JOHN    WILEY    &    SONS, 

53  East  Tenth  Street. 
1894. 


Copyright,  1884, 
By  J.  A.  L.  WADDELL. 


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PREFACE. 


This  work  is  principally  a  compilation  of  the  results  of  inve:tigations 
made  by  the  author  during  the  last  three  years,  and  presented  in  a 
number  of  papers  to  the  various  American  engineering  societies.     Sev- 
eral  port.o..  of  the  book,  including  many  of  the  tables,  are  new.  as 
th.s  ,s  the  first  systematic  treatmeni.  by  the  author,  of  bridges  for  cities 
and  manufacturing  districts;  the  previous  papers  havmg  dealt  especially 
w.th  those  for  country  roads.     In  ..aking  this  compilation,  the  author 
has  been  governed  by  no  blind  adherence  to  what  he  has  alrea'dy  writ- 
ten but    as  made  changes  wherever  they  have  appeared  to  be  advisable 
One  o    the  ch.ef  objects  of  this  work  is  to  reduce  the  labor  of  iron 
h.g  way  bndge  designing  to  a  minimum,  for  which  purpose  every  thing 
that  cou  d  be  so  arranged  has  been  tabulated.     Not  only  are  the  exact 
sues  of  h.p  verticals   joists,  floor  beams,  beam  hangers,  lateral  rods  and 
truts,  portal  rods  and  struts,  vibration  rods,  intermediate  struts,  lattice 
bars,  stay  plates,  etc..  given  for  all  practical  cases,  but  also  the  most 
economic  d„.ensions  of  panels  and  trusses,  and  dead  loads,  so  exact 
ha    by  the,r  use  all  necessity  for  a  second   trial  is  avoided.      These 
2^  .t  IS  hoped,  will  prove  useful  to  those  in  the  actual  practice  of 
ndge  des,gnu.g.  enabling  them  to  greatly  reduce  the  time  required 
to  make  diagrams  of  stresses  and  sections  and  estimates  of  cost      The 
other^tables.  although  they  do  not  give  final  result,  should  also  be  of 

The  value  of  the  book  may  appear  to  some  readers  to  be  limited,  in 
that  ,t  treats  of  only  the  Pratt  and  Whipple  systems;  but  it  must  be 


IV 


PREFACE. 


reineml)ered  that  at  least  ninety  per  cent  of  all  American  iron  highway- 
bridges  are  built  on  these  systems.  This  fact  alone  ought  to  prove 
conclusively  that  they  are  the  best  type  of  bridge.  Moreover,  the 
author  has  demonstrated,  in  a  paper  entitled  "  Economy  in  Struts 
and  Ties,"  published  last  year  in  the  "  Canadian  Magazine  of  Science," 
and  copied  in  the  "  American  Engineer,"  by  a  method  entirely  practical, 
that  for  economy  the  web  compression  members  of  trusses  should  be 
vertical,  or  nearly  so ;  thus  showing,  that,  of  all  the  ordinary  types  of 
truss,  the  Pratt  or  Whipple  is  the  best. 

Through  bridges  and  pony  trusses,  both  having  inclined  end  posts, 
have  alone  been  treated  at  length ;  for  highway  deck  bridges  are  un- 
common, and  inclined  end  posts  not  only  are  more  economical  than 
vertical  ones,  but  are  also  superior  to  them  because  they  produce  tensile 
stresses  in  the  end  panels  of  the  bottom  chords,  thus  ailding  to  the 
rigidity  of  the  structure. 

The  work  is  written  for  engineers,  students,  and,  to  a  certain  extent, 
county  commissioners.  It  is  not  intended,  though,  to  be  used  by  itself 
as  a  text-book  on  bridges,  dealing,  as  it  does,  with  only  one  general 
style  of  triiss,  but  to  supplement  the  books  generally  used  by  classes 
in  engineering  schools. 

It  is  essentially  a  treatise  upon  bridge  designing,  and  not  one  upon 
stresses :  nevertheless,  it  has  been  found  necessary  to  discuss  the  latter 
subject  in  order  to  make  the  work  comjjlete.  The  author  would  refer 
those  who  wish  to  study  concerning  stresses  to  Burr's  "  Stresses  in 
Bridge  and  Roof  Trusses,"  Bovey's  "Applied  Mechanics,"  and  I)u 
Bois'  "  Strains  in  Framed  Structures." 

For  county  commissioners.  Chapters  IV.,  XIV.,  and  XVII.,  Tables 
I.-V.,  XV.-XXV.,  XXX.-XXXIII.,  and  XXXVIII.,  and  parts  of  Chap- 
ter II.,  will  be  found  very  useful ;  containing,  as  they  do,  directions  and 
data  for  making  estimates  of  cost,  and  means  of  proving  whether  either 
designs  or  finished  structures  have  or  have  not  in  many  particulars 
sufficient  strength. 

Those  portions  of  the  "General  Specifications"  in  Chapter  II., 
relating  to  quality  and  tests  of  materials,  workmanship,  painting,  etc., 
have  been  taken  from  standard  specifications  too  numerous  to  permit 


PREFACE. 


of  their  autliority  being  here  quoted :  nevertheless,  the  author  must 
atkiu)wlf(Igf  that  he  has  received  considerable  assistance  from  a  pa])or 
by  Mr.  1'.  F.  Brcndlinger  published  in  No.  4,  vol.  iii.,  of  the  "Proceed- 
ings of  the  Engineers'  Club  of  Philadelphia,"  treating  of  some  railroad- 
bridge  specifications  prepared  by  Theodore  Cooper,  C.E.  He  wishes 
to  acknowledge  also,  with  many  thanks,  the  valuable  aid  rendered  him 
by  his  assistants,  Messrs.  Y.  Nakajima  and  T.  Fukuda,  in  preparing 
drawings,  and  checking  tables. 

J.  A.   L.   W. 

ToKio,  Japan,  February,  1884. 


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PREFACE  TO  SECOND  EDITION. 


Although  the  first  edition  of  this  work  was  issued  only  three  or 
four  months  ago,  it  has  had  the  opportunity  for  receiving  a  thorough 
overhauling  by  a  class  of  half  a  dozen  students,  who  were  requested 
to  take  special  pains  to  point  out  errors.  A  few  were  found;  but 
they  are  of  small  importance,  being  principally  typographical  or 
numerical.  It  is  thought  that  all  have  been  discovered  and  corrected, 
but  it  is  possible  that  others  may  exist :  so,  if  any  reader  find  any,  he 
will  confer  a  favor  upon  the  author  by  informing  him  of  the  same. 

The  correctness  of  the  weights  of  iron  in  Tables  I.,  II.,  and  III., 
has  received  additional  confirmation  from  the  same  class  of  students, 
each  student  having  made  a  complete  design  for  a  bridge.  The  great- 
est variation  found  was  less  than  one-half  of  one  per  cent.  As  the 
bridges  varied  in  class,  span,  and  width  of  roadway,  one  being  on  a 
skew,  and  two  having  sidewalks,  it  is  fair  to  conclude  that  the  tables 
may  be  relied  upon  as  correct  for  all  cases. 

A  slight  change  has  been  made  in  Chapter  V.,  near  the  end,  in  respect 
to  a  statement  concerning  stresses  in  the  posts  of  deck  bridges ;  but,  for 
reasons  there  stated,  the  formula  has  not  been  altered. 

In  a  review  of  this  treatise,  by  "  The  American  En^neer;'  there  was 
mentioned  the  fact  that  double  beam  hangers  are  not  a  satisfactory 
detail,  because  of  the  unequal  distribution  of  the  floor-beam  load  there- 
on. In  the  addenda  is  described  a  detail  which  will  remove  the  objec- 
tion. There  are  given  also  in  this  part  of  the  work,  and  on  Plate  VIII., 
several  other  details  that  will  be  found  to  be  improvements  upon  those 
previously  described.  ,, 


vm 


i'Ri:rACE  TO  sEco.xn  edition. 


About  July  I,  tlicre  will  be  issued  by  the  University  of  Toklo,  In  the 
form  of  the  usual  "Memoir,"  a  treatise  of  the  author  upon  "A  System 
of  Iron  Railroad  Bridges  for  Japan,"  which  will  be  found  to  contain  a 
nun  )er  of  important  matters  respecting  the  designing  of  railroad- 
bridges,  that  have  not  hitherto  received  proper  attention.  The  book  is 
not  for  sale  ;  but  there  will  be  alwut  two  hundred  copies  distributed  in 
America  among  engineers,  colleges,  public  libraries,  etc. 

The  author  wishes  to  express  his  thanks  to  the  profession  for  the 
favorable  reception  given  to  his  fust  edition. 

J.  A.  L.  W. 
ToKio,  Japan,  May  6,  1885. 


PREFACE  TO  THIRD  EDITION. 


It  is  with  considerable  regret  that  the  author  allows  this  edition  to 
go  to  press  without  making  a  single  change  or  addition,  more  especially 
because  his  practice  in  bridge  designing  has  lately  been  modified. 
Time  will  not  permit  of  his  rewriting  the  work  for  a  year  or  two  at 
least,  so  it  will  have  to  remain  as  it  is  for  the  present.  The  changes 
which  he  would  like  to  introduce  in  the  text  are  not  in  principles,  init 
in  methods  and  details  of  design ;  American  practice  having  changed 
somewhat  since  thj  book  was  first  written.  These  points  s^'ll  all  be 
covered  by  some  general  specifications,  which  the  author  expects  to 
issue  in  a  few  months.  They  will  probably  be  for  sale,  and  advertised 
in  "  Engineering  Neros." 

The  priiuii)al  changes  in  his  methods  are  the  following  :  — 

I  St,  For  long  spans  it  is  better  to  use  the  Pratt  truss,  with  halved 
panels,  instead  of  the  Whipple  truss.  In  spans  exceeding  two  hundred 
feet,  it  is  economical  to  make  portions  of  the  top  chords  inclined. 

For  short  spans  it  is,  in  general,  well  to  use  rolled  beams  up  to 
twenty  feet,  plate  girders  from  twenty  to  forty  feet,  triangular  riveted 
girders  from  forty  to  sixty-five  feet,  pin-connected  pony  trusses  from 
sixty-five  to  ninety  feet,  and  pin-connected  throug'^  or  deck  truss 
bridges  from  ninety  feet  upward. 

2d,  Tlie  batter  braces  (or,  as  they  are  now  being  generally  termed, 
the  inclined  end  posts)  are  hinged  at  hip  and  pedestal. 

3d,  Floor  beams  are  riveted  to  posts  as  near  the  lower  chords  as 
possible,  and  the  lateral  rods  are  attached  to  the  lower  part  of  the 
beams.  The  wooden  shims  over  beams  are  retained  for  the  purpose 
of  spiking  the  joists  thereto. 

ix 


PREFACE    TO   THIRD  EDITIO.W 


4th,  Filling-plates  under  floor  beam  stiffeners  are  no  longer  necessary, 
as  it  is  now  very  easy  to  Ijend  the  ends  of  the  angles  to  fit  around  the' 
flanges  of  the  beams.  It  is  permissible  to  stagger  intermediate 
stiffeners.  End  stiffeners  should  be  figured  for  the  total  shear,  using 
an  intensity  of  three  tons  for  bridges  of  Class  A,  and  three  and  three- 
quarter  tons  for  bridges  of  Classes  B  and  C. 

5  th,  Upper  lateral  and  portal  struts  are  made  of  four  angle -irons, 
with  a  single  system  of  lacing-bars.  These  struts  are  rigidly  connected 
to  top  chords  or  inclined  end  posts  by  riveting. 

6th,  End  lower  lateral  struts  can,  in  general,  l^e  made  of  single 
angle-iron  of  large  size.  It  is  preferable  to  use  one  of  these  struts  at 
each  end  of  every  span.  They  can  be  riveted  to  the  pedestals  by 
means  of  a  connecting-plate  at  each  end. 

7th,  Lacing  is  used  everywhere  instead  of  latticing. 
8th,  Rivets  are  figured  for  shear  and  bearing,  not  for  bending. 
9th,  In   many   cases   flattened    heads   may   be   used   to   advantage, 
instead   of   countersinking    the    rivets,   the    thickness    of    the    heads 
being  three-eighths  of  an  inch. 

lotli,  Lateral  rods  are  attached  at  each  end  to  top  chord  by  means 
of  three  short  pieces  of  angle-iron,  through  one  of  which  the  rod 
passes.  Tlie  adjustment  is  made  by  a  nut  at  each  end,  which  bears 
against  the  last  mentioned  angle-iron. 

nth,  In  top-chord  splicing,  reliance  is  placed  upon  the  abutting 
ends  of  the  chord  sections.  The  splice  is  made  about  fifteen  or 
eighteen  mches  from  the  panel  point  on  the  side  towards  the  nearer 
pier,  and  there  are  only  two  vertical  rows  of  rivets  in  the  splice  i)late 
on  each  side  of  the  joint  The  shop  practice  of  first-class  bridge 
companies  has  improved  so  much  during  the  past  five  years,  that  it 
is  now  legitimate  to  rely  upon  abutting  ends  for  this  detail.  Never- 
theless, the  author  would  prefer  to  hinge  the  top  chord  at  each  panel 
point,  for  in  this  case  there  can  be  no  doubt  as  to  how  the  stresses 
travel.     The  same  cannot  be  said  for  any  other  style  of  connection. 

1 2th,  When  a  bridge  is  sufficiently  heavy,  it  is  well  to  build  the  toj) 
chords  and  inclined  end  posts  of  plates  and  angles,  using  small,  lioht 


PREFACE   TO   THIRD  EDITION. 


XI 


angles  above,  and  large,  heavy  angles  below,  so  as  to  bring  the  centre 
of  gravity  of  the  section  to  the  middle  of  the  vertical  plate. 

13th,  For  hip  verticals  it  is  preferable  to  use  a  strut  of  two  channels 
similar  to  the  posts,  but  not  so  efficiently  laced,  as  the  member  acts 
only  in  tension.     Channels  provide  greater  rigidity  than  do  eye-bars. 

14th,  In  proportioning  compression  members,  Thacher's  formula  is 
used  instead  of  that  of  the  late  C.  Shaler  Smith.     It  is  the  following :  — 


/  = 


9,000  —  30  -  for   O    D 


9,000  -  35-  for   D    O 


9,000  —  40-  for  O   O 
r 


where  /  is  the  intensity  of  working  stress  in  pounds,  /  the  un.supported 
length  of  strut  in  inches,  and  r  the  radius  of  gyration  of  section  in 
inches.  The  above  formula  is  for  bridges  of  Class  A.  To  use  it  for 
Classes  B  and  C,  multiply/  by  \  ;  and  to  use  it  for  lateral  struts,  multiply 
/  by  |.  In  the  latter  case,  however,  considerations  of  rigidity  generally 
necessitate  the  use  of  greater  sectional  area  than  the  stress  would  call 
for. 

15th,  In  order  to  be  in  accordance  with  modern  practice,  floor 
beams  should  be  proportioned  by  neglecting  the  resistance  of  the  web 
to  bentling,  and  using  an  intensity  of  five  tons  for  finding  the  ttct  area 
of  the  bottom  flange  in  bridges  of  Class  \,  and  six  tons  for  bridges  of 
Classes  B  and  C,  then  making  tlie  upper  flange  of  the  same  section 
as  the  lower,  taking  care,  however,  to  have  the  ratio  of  unsupported 
lengtii  of  beam  to  width  of  flange  not  greater  than  thirty. 

In  the  author's  opinion  this  method  is  not  so  rational  as  the  one 
which  he  used  formerly,  but  it  is  more  easily  applied  and  gives  about 
the  same  results. 

Strictly  speaking,  the  web  of  a  built  beam  does  aid  the  flanges  to 
resist  bending;  but,  in  truth,  the  designing  of  built  beams  and  girders 
pertains  less  to  science  than  to  rule  uf  tiiumb. 


Xll 


PREFACE  TO  THIRD  EDITION, 


1 6th,  Bent  eyes  on  rods  are  no  longer  allowed, 

i7tli,  In  every  thing  relating  to  quality  of  material,  workmanship, 
inspection,  and  tests,  the  Manufacturers'  Standard  Specifications  are 
to  be  followed. 

The  author  trusts  that  the  preceding  lemarks,  together  with  his 
new  specifications,  will  keep  his  book  from  becoming  antiquated  until 
he  can  find  time  for  re-writing  the  whole  treatise. 

J.  A.  L.  W. 

Kansas  City,  Mo.,  July  i6,  1887. 


PREFACE  TO  FOURTH  EDITION. 


Again  with  great  regret  does  the  author  permit  this  work  to  reach 
another  edition  without  receiving  a  thorough  revision,  amounting,  in 
fact,  to  a  complete  re-writing  of  the  book.  The  past  year  has  been 
such  a  busy  one,  that  it  was  impossible  for  him  to  spare  the  necessary 
time. 

The  new  specifications  promised  in  the  last  preface  have  been  issued, 
and  are  now  on  sale  by  Mr.  A.  C.  Stites,  Walworth  Building,  Kansas 
City,  Mo.,  the  price  being  twenty-five  cents  per  copy. 

The  author  would  advise  that  these  be  used  in  connection  with  this 
book,  and  that,  where  they  conflict,  the  new  specifications  be  followed. 
It  will  be  seen  that  the  latter  contain  considerably  more  than  mere 
si)ecifications,  being  a  systematic  attack  upon  the  present  methods  of 
tlesigning,  letting,  and  building  highway  bridges.  The  pamphlet  is 
being  well  advertised  and  distributed  aniong  county  commissioners  ;  and 
the  author  is  sparing  neither  time,  trouble,  nor  expense  to  accomplish 
the  reform  which  he  deems  so  necessary. 

The  re-writing  of  this  treatise  has  already  been  begi;n  ;  but  there  is 
no  telling  when  it  will  be  completed,  for  the  author's  spare  time  is 
very  limited.  He  hopes,  however,  that  it  will  be  be  finished  before  a 
fifth  edition  becomes  necessary. 

J.  A.  L.  W. 
Kansas  City,  Mo.,  April  u,  1888. 


CONTENTS. 


Chapter. 

,     ,  Page. 

I.  Introduction 

••••••••       I 

II.  General  Specifications      .... 

III.  List  of  Members 

28 

IV.  Live  AND  Dead  Loads.  — Wind  Pressure        ....         ,2 

V.  Stresses  in  Trusses  . 

38 

VI.  Stresses  in  Lateral  Systems  and  Vertical  Sway  Bracing  .  48 

VIL  Remarks  concerning  Main  Members 

Vin.  Proportioning  of  Main  Members  of  Trusses,  Lateral' Sys^ 

TEMs,  AND  Sway  Praclng         .  ^ 

00 

IX.  Proportioning  of  Floor  System ^ 

X.  Theory  of  Pin  Proportioning g 

XL  Practical  Method  of  Pin  Proportioning g. 

XIL  Riveting 

90 

Xin.  Proportioning  of  Other  Details 

XIV.  Bills  OF  Materials  AND  Estimates  OF  Cost  .       ...        114 

XV.  Economy 

120 

XVI.  Complete  Design  for  a  Bridge ,,5 

XVIL  Bridge  Lettings 

157 

XVIII.  Working-Drawings 

172 

XIX.  Order  Bills  and  Shipping  Bills jg, 

XX.   Erection  and  Maintenance j_g 

APPENDIX    I.     A   Neglected  Consideration    in    Highway-Bridge 

Designing  . 

215 

APPENDIX  II.    Demonstration  of  Formula  for  Floor  Beams    .        219 
APPENDIX  III.    Method  of    Finding    the  Length    of    the  Long 

Diagonals  in  a  Double-Intersection  Bridge  .        .  ,21 

ADDENDA ... 

GLOSSARY  OF  TERMS        .  * "5 

INDEX 233 

.        .        .         247 


INDEX  OF  TABLES. 


i.-iii. 

IV.,  V. 

VI.-VIII. 

IX. 

X.,  XI. 

XII. 

XIII.,  XIV. 

XV.-XVIII. 

XIX.-XXI. 

XXII.-XXIV. 

XXV. 


XXVI.,  XXVII. 

XXVIII. 

XXIX. 

XXX. 

XXXI. 

XXXII.,  XXXIII. 

XXXIV.,  XXXV. 

XXXVI.,  XXXVII. 

XXXVIII. 

XXXIX. 

XL. 

XLI. 

XLII. 


Dead  Loads. 

Economic  Depths  and  Tanel-Lengths. 

Sizes  of  Hip  Verticals. 

Working  Tensile  Stresses  and  Initial  Tensions. 

Intensities  OF  Working-Stresses  for  Channel  Struts, 

Working  Bending-Moments  and  Shearing-Resist- 
ances for  Tins. 

Working  Loads  for  Wooden  Beams. 

Amounts  of  Lumher  per  Panel,  Sizes  of  Joists,  etc. 

Sizes  and  Weights  of  Floor-Beams. 

Sizes  of  Beam-IIangers. 

Sizes  of  Portal,  Lateral,  and  Intermediate  .Struts, 
and  of  Upper  Lateral,  Lower  Lateral,  and  Vibra- 
tion Rods. 

Thicknesses  for  Pin-Bearings. 

Dimensions  of  Union  Iron  Mills'  Channel-Bars. 

Lengths  of  Lattice-Bars,  Weights  per  Foot  of  Same, 

ETC. 

Sizes  of  Lattice-Bars. 

Sizes  of  Lacing-Bars. 

Sizes  of  Stay  Plates. 

Permissible  Pressures  on  Rollers. 

Working  Bending-Moments   and  Bearing-Pressures 

FOR  Rivets. 
Laisor  in  Erection. 

Working  Loads  for  Falsework  Pillars. 
Working-Loads  for  J-Beam  Struts. 
Stresses  in  Single-Intersection  Trusses. 
Stresses  in  Double-Intersection  Trusses. 


XV 


INDEX  OF  PLATES. 


I.    Isometric  Drawing  of  a  Bridge  with  Names  of  Main  Members. 
II.    General  Descriptive  Plate  of  Details. 

III.  Details  for  a  Pony  Truss-Bridge. 

IV.  Details   for  a  Single-Intersection  Through  City  Bridge  with 

Two  Sidewalks. 
V.    Diagram  of  Stresses  and  Sections. 
VI.    Working-Drawings  for  a  Bridge. 

VII.  Working-Drawings  for  Falsework. 

VIII,  Details  Illustrating  the  AnnENDA. 


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THE    DESIGNING 


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ORDINARY   IRON   HIGHWAY-BRIDGES. 


CHAPTER   I. 


INTRODUCTION. 

That  many  bridge  designers  will  have  fault  to  find  with  the 
contents  of  this  book  goes  without  saying,  but  it  will  be  found 
that  the  principal  objections  will  come  from  those  who  design 
the  lightest  and  poorest  structures.  The  weights  of  iron  in  the 
bridges  here  treated  are  probably  from  twenty  to  fifty  per  cent 
greater  than  those  in  the  bridges  ordinarily  built  ;  but  it  is  to 
be  remembered  that  most  American  iron  highway-bridges  are 
not  what  they  ought  to  be,  and  that  the  author  has  endeavored 
to  design  structures  first-class  in  every  respect. 

The  principal  differences  between  these  bridges  and  those 
ordinarily  built  are  the  stiffening  of  the  end  panels  wherever 
necessary  ;  the  use  of  C.  Shaler  Smith's  formula,  involving,  as  it 
generally  does,  an  increase  of  sectional  area  ;  the  peculiar  lower 
lateral  system,  which  avoids  using  the  floor  beams  as  lateral 
struts  ;  the  large  lateral  rods  employed  ;  the  allowance  for  initial 
tension  in  all  adjustable  rods;  the  variation  of  the  intensity 
of  working-stress  for  main  diagonals  ;  the  assumption  that  all 
stresses  at  joints  in  top  chords  and  at  upper  ends  of  posts  are 
carried  by  the  connecting  plates  and  their  rivets,  no  reliance 
bemg  placed  upon  the  abutting  ends  of  channels  ;  the  limiting 
sizes  of  the  sections  of  iron  employed  ;  and  the  unusual  strength 


O/WJAAKy  JKOA'  JiiuliWAV-nKIDuES. 


of  the  upper  lateral  and  portal  struts,  especially  when  no  verti- 
cal sway  bracinj;  is  usctl. 

On  the  other  hand,  those  who  wish  to  proportion  bridges  by 
the  latest  theories  may  object  to  the  employment  of  C!  Shaler 
Smith's  formula  (which  fails  to  take  into  account  the  radius 
of  gyration  of  the  section)  and  to  the  non-employment  of  the 
results  of  Wohler's  and  Weyrauch's  recent  investigations  con- 
cerning intensities  of  working-stresses.  To  the  first  objection, 
the  author  would  reply,  that  designers  of  ordinary  highway- 
bridges  cannot  afford  the  time  to  spend  at  least  fifteen  minutes 
in  obtaining  the  theoretically  best  intensity  of  working-stress  for 
each  strut,  but  must  have  for  this  pur|)ose  tables  which  will  ^ive 
the  intensities  without  calculation  :  besides,  the  best  theoretical 
intensity  is  merely  approximate.  To  the  second  objection,  he 
would  reply,  that  the  results  of  the  investigations  rcfeired  to 
have  not  yet  been  generally  adopted,  and  that  the  variation  of 
intensity  of  working-stress  for  the  main  diagonals  used  in  tiiis 
treatise  is,  in  his  opinion,  for  ordinary  highway-bridge  design- 
ing, a  sufficient  concession  to  the  general  correctness  of  the 
theory  of  those  writers. 

The  units  used  throughout  this  work  are  as  follows :  the 
American  ton  (two  thousand  pounds)  for  the  units  of  weight 
and  stress,  the  foot  for  the  unit  of  length,  and  the  square  inch 
for  the  unit  of  area. 

It  is  presupposed  that  the  reader,  if  he  intend  to  design,  or 
even  study  the  designing  of,  iron  bridges,  has  procured  a  copy 
of  Carnegie's  "  Pocket-Companion,"  the  most  useful  little  book 
of  its  kind  for  bridge  builders  that  has  ever  been  printed  :  so 
the  tables  therein  are  here  referred  to,  instead  of  being  repro- 
duced. 

The  sections  of  iron  employed  arc  those  rolled  at  the  Union 
Iron  Mills,  for  the  reason  that  not  only  is  there  more  iron  rolled 
in  these  mills  than  anywhere  else  in  America,  but  the  proper- 
ties of  the  sections  arc  tabulate''  n  a  mnch  more  convenient 
form  than  are  those  of  any  othe*  n;il'<.  The  author  intended 
to  prepare  a  table  of  channels  ,i  !  by  the  New-Jersey  Steel 
and  Iron  Company  of  Trenton,  N.J.,  similar  to  Table  XXVIII.  ; 
but    the    information    in    that    company's   pocket-book    is    not 


II  IK)  vcrti- 


CSS  of  the 


OA'D/A'Afiy  /A'ox  nn;n\\'Av-niuiH;Es.  3 

complete  enou-h  to  enable  him  to  tabulate  the  thicknesses  of 
the  webs. 

Anyone  intending  to  desijrn  bridges  according  to  the  method 
herein  proposed  should  thoroughly  acquaint  himself  with  the 
numbers  and  uses  of  the  different  tables,  so  as  to  turn  to  the 
one  required  without  delay.  He  should  also  become  posted  on 
the  contents  of  Chapters  VII.-XIII.,  so  as  not  to  have  to  refer 
to  that  part  of  the  book,  turning  to  Chapter  II.  to  refresh  his 
memory  concerning  intensities  of  working-stresses,  limitations. 
etc.,  while  designing  each  main  member  and  detail.  After  a 
little  practice,  one  will  become  acquainted  with  the  method, 
when  it  will  be  necessary  to  refer  to  the  tables  only. 

If  a  designer  be  in  doubt  about  how  to  proportion  any  main 
member  or  detail,  he  can  at  once  find  out  the  method  by  look- 
ing  in  the  Inde.x,  under  the  head  "Proportioning,"  where  he 
will  see  the  numbers  of  the  pages  on  which  the  proportioning 
of  this  member  or  detail  is  treated. 

Any  intelligent  man  who  is  not  an  engineer  can  make  an 
approximate  estimate  of  what  a  first-class  iron  highway-bridge 
ought  to  cost,  by  finding  the  required  weight  of  iron  from  one  of 
Tables  I.,  II.,  or  III.,  modifying  it,  if  neces.sary,  in  the  manner 
explained  in  Chapter  IV. ;  and  the  required  amount  of  lumber 
from  one  of  Tables  XV.,  XVI.,  XVII.,  or  XVIII..  ascertaining 
the  prices  of  iron  per  pound,  and  lumber  per  thousand  feet° 
delivered  at  the  nearest  railway-station  or  seaport,  and  filling 
out  the  form  for  an  estimate  of  cost  given  on  p.  1 16.  By  refer- 
ring to  the  Index,  under  the  heading  "Cost,"  he  can  ascertain 
where  approximate  data  for  all  bridge-building  expenses  can  be 
found. 

No  special  treatment  is  here  given  for  skew  bridges  ;  for  none 
is  needed,  the  methods  for  designing  them  being  precisely  the 
same  as  those  for  other  bridges.  On  account  of  the  obliquity, 
the  working  drawings  for  the  lateral  bracing  and  sway  bracino- 
are  a  little  more  complicated.  Whenever  it  is  convenient  to  do 
so,  the  panel  lengths  should  be  arranged  so  that  the  shoe  of 
one  truss  comes  opposite  to  the  first  panel  point  of  the  other 
truss,  in  order  that  the  floor  beams  may  be  at  ri-ht  angles 
to  the  planes  of  the  trusses,  both  for  economical  reasons,  and  to 


ORDIXARY  IRON  HIGHV'AY-BRIDGES. 


avoid  using  single  beam  hangers.  This  arrangement  can  often 
be  made  by  shortening  the  panel  length  a  little,  and,  if  it  be 
allowable,  slightly  changing  the  angle  of  the  skew.  Even  if  it 
be  impracticable  to  make  this  arrangement,  it  is  usually  better, 
in  skew  bridges,  to  advance  the  ends  of  the  floor-beams  at  one 
side  of  the  bridge,  by  one  or  even  two  panel  lengths,  if,  by  so 
doing,  the  floor  beams  be  shortened. 


ORDINARY  IRON  HIGHWAY-BRIDGES. 


CHAIT'ER    II. 


GENERAL   SPECIFICATIONS. 


This  chapter,  at  first  thought,  may  appear  out  of  place  ;  for  it 
is  really  a  n'siivic  of  the  whole  subject  of  iron  highway-bridge 
designing.     It  is  placed  here  in  order  to  be  of  easy  reference. 

Students,  and  those  unacquainted  with  bridge  designing,  are 
advised  to  omit  these  specifications,  and  to  return  to  them  after 
having  read  through  Chapter  XIII. 

Classification.  —  Highway-bridges  maybe  divided  into  three 
classes  ;  viz.,  Class  A,  which  includes  those  for  cities  and  their 
suburbs  that  are  subjected  to  the  continued  dL\)X)\\c:xt\on  of  heavy 
loads  ;  Ciu.is  B,  which  includes  those  for  cities  and  their  suburbs, 
or  manufacturing  districts,  that  are  subjected  to  the  occasional 
application  of  heavy  loads  ;  and  Class  C,  which  includes  those 
for  country  roads,  where  the  traffic  is  lighter. 

Live  Load. — The  live  loads  for  bridges  of  the  different 
classes  are  to  be  taken  from  the  followins  table:  — 


SPAN  IN  FEET. 

Moving  Load  per  Square  Foot  of  Floor. 

Classes  A  and  B. 

Class  C. 

0  to    50 

50  to  I  50 

I  50  to  200 

200  to  300 

300  to  400 

100  pounds 
90  pounds 
80  pounds 
70  pounds 
60  pounds 

80  pounds 
80  pounds 
70  pounds 
60  pounds 
50  pounds 

The  live  loads  for  joists,  floor  beams,  beam  hangers,  and  hip 
verticals,  are  to  be  one  hundred  (100)  pounds  per  square  foot  of 
floor  for  bridges  of  Classes  A  and  \\,  and  eighty  (80)  pounds  per 


6 


OKD/A\l/n-  /J^O.y  JIIullWA  V-B RIDGES. 


square  foot  for  bridges  of  Class  C,  irrespective  of  the  length  of 
bridge. 

DiacfLoad—Tho  dead  load  is  to  include  the  weight  of  all 
the  iron  and  wood  in  the  structure,  excepting  that  of  those  por- 
tions resting  directly  on  the  abutments,  whose  weights  do  not 
affect  the  stresses  in  the  trusses  ;  also,  if  necessary,  an  allow- 
ance for  snow,  mud.  paving,  or  any  other  unusual  fixed  load 
that  may  ever  be  placed  on  the  bridge. 

Pine-lumber  is  assumed  to  weigh  two  and  a  half  (2.1)  pounds 
per  foot,  board  measure  ;  and  oak-lumber,  fotir  and  a  third  (4^) 
pounds  per  foot,  board  measure. 

:  Should,  in  any  biidge  of  or  below  one  hundred  (100)  feet 
span,  the  calculated  dead  load  differ  more  than  eight  (8)  per 
cent  from  that  assumed,  or  in  any  bridge  from  one  hundred 
(100)  to  two  hundred  (200)  feet  span,  more  than  six  (6)  per 
cent,  or  in  any  bridge  exceeding  two  hundred  (200)  feet  span, 
more  than  four  (4)  per  cent,  the  calculations  of  stresses,  etc., 
are  to  be  made  over  with  a  new  assumed  dead  load. 

IViiui Prcssiin:— The  wind  pressure  per  square  foot  i.s  to 
be  assumed  as  forty  (40)  pounds  for  spans  of  one  hundred  (100) 
feet  and  under,  thirty-five  (35)  pounds  for  spans  over  one  hun- 
dred (100)  and  not  greater  than  one  hundred  and  fifty  (150) 
feet,  and  thirty  (30)  pounds  for  all  greater  spans. 

For  bridges  in  unusually  exposed  situations,  these  pressures 
are  to  be  increased  by  ten  (10)  pounds  per  square  foot. 

The  total  area  opposed  to  the  wind  is  to  be  determined  by 
adding  together  the  area  of  the  vertical  projection  of  the  floor 
and  joists,  and  twice  the  area  of  the  vertical  projection  of  the 
windward  truss,  hand  rail,  hub  plank,  guard  rail,  and  ends  of 
floor-beams. 

Laigt/t  of  Span.  —  The  length  of  span  is  to  be  understood 
as  the  distance  between  centres  of  end  pins  for  trusses,  and 
between  centres  of  bearing-plates  for  all  beams  and  girders. 

Umitiiii;  Lengths  of  Span  for  Different  Clear  Roadzvavs.  — 
The  greatest  lengths  of  span  for  the  different  clear  roadways 
are  to  be  one  hundred  and  forty  (140)  feet  for  twelve  (12)  foot 
roadways,  one  hundred  and  ninety  (190)  feet  for  fourteen  (14) 
foot  roadways,   two  hundred   and   sixty  (260)  feet   for  sixteen 


ORDINARY  IROX  HIGHlVAY-liRlDGES.  7 

(16)  foot  roadways,  and  three  hundred  and  fifty  (350)  feet  for 
eighteen  (18)  foot  roadways.  By  clear  roadway  is  meant  the 
tlistance  between  the  innermost  portions  of  the  opposite  trusses, 
measured  in  a  direction  perpendicular  to  their  planes. 

Limit  of  Char  Hcadivay.  —  The  least  allowable  clear  head- 
way is  to  be  fourteen  (14)  feet,  unless  some  local  consideration 
cause  it  to  be  increased.  \\y  clear  headway  is  meant  the  ver- 
tical distance  between  the  upper  face  of  the  flooring  and  the 
lowest  part  of  the  portal  or  overhead  bracing. 

Styles  of  Bridges  for  Different  Spans.  —  Spans  of  and  belo>v 
twenty  (20)  feet  are  to  consist  of  rolled  beams  ;  spans  from 
twenty  (20)  to  forty  (40)  feet,  of  riveted  plate  girders  or  trussed 
beams ;  spans  from  forty  (40)  to  si.xty-five  (65)  feet,  of  stiffened 
pony  trusses  or  stiffened  deck  bridges,  unless  the  weight  of 
bridge  be  great  enough  to  admit  of  the  use  of  eye  bars  for  the 
bottom  chords  ;  and  spans  above  sixty-tive  (65)  feet,  of  pin- 
connected  through  or  deck  truss  bridges. 

Limiting  Depth  of  Pony  Trusses. —T\^ii  greatest  allowable 
depth,  measured  from  centre  to  centre  of  chords,  for  pony 
trusses  without  exterior  side  bracing,  is  to  be  six  (6)  feet  ;  and 
that  for  pony  trusses  with  exterior  side  bracing,  nine  (9)  feet. 
Vw  bridges  with  sidewalks,  in  which  it  is  inconvenient  to  use 
exterior  side  braces,  the  depth  may  be  increased  to  eight  (8) 
feet,  provided  that  the  width  of  the  top  chord  plate  be  double 
the  dejith  of  the  top  chord  channels,  and  that  the  channels 
comjiosing  the  posts  and  hip  verticals  be  splayed  outwartlly  so 
as  to  be  separated  in  the  clear  at  their  feet  by  at  least  twenty- 
four  (24)  inches. 

Limiting  Slope  for  Batter  Braces  of  Pony  Trusses.— i:\\<t  least 
allowable  slope  for  batter  braces  of  pony  trusses  is  to  be  two 
and  a  quarter  {2])  horizontal  to  one  (1)  vertical. 

Side  Fumes.  —  The  least  allowable  batter  for  side  braces  in 
pony-truss  bridges  is  to  be  five  (5)  inches  to  the  foot,  and  all 
sitle  braces  are  to  be  made  to  resist  both  tension  and  compres- 
sion. In  no  case  is  a  side  I'race  to  have  less  strength  than  that 
of  a  2^"  X  2»"  5-lb.  angle-iron. 

Limiting  Length  of  Span  for  Double  Interseetion  Btidges.  ~ 
The  least  allowable  length  of  span  for  double  intersection 
bridges  is  to  be  taken  from  the  fdlldwin-"  table:  — 


ORDINARY  IROX  HIGniVAY-BRinGKS. 


CLEAR  ROADWAY. 

I.i.MiTJNc;  Lkni;tiis. 

Class  A. 

Class  B. 

Class  C. 

14' 
16' 
18' 
20' 
22' 
24' 

i6s' 

•55' 
150' 

145' 
140' 
140' 

175' 
165' 
160' 

155' 
ISO' 

•45' 

180' 
170' 
165' 
160' 

■55' 
150' 

Limiting  Sizes  of  Sections.  —  No  rods  less  than  three-quar- 
ters (|)  of  an  inch  in  diameter  are  to  be  used  in  a  bridge.  No 
channels  less  than  five  (5)  inches  in  depth  are  to  be  used  for 
upper  chords,  batter  braces,  or  posts,  or  less  than  four  (4)  inches 
in  depth  for  other  members.  No  flat  bars  less  than  one-half  {I) 
inch  thick,  or  one  and  a  half  (i^)  inches  wide,  are  to  be  used 
for  diagonals  or  chord  bars  ;  nor  any  iron  less  than  one-quarter 
(|)  of  an  inch  thick  anywhere  in  a  bridge,  excepting  for  filling 
plates. 

Expansion. — All  spans  are  to  be  provided  with  some  means 
of  expanding  and  contracting  longitudinally,  with  a  variation  in 
temperature  of  one  hundred  and  fifty  (150)  degrees  Fahrenheit. 
Spans  of  over  seventy-five  (75)  feet  are  to  have  at  one  end  nests 
of  turned  wrought-iron  friction  rollers,  running  between  planed 
surfaces. 

Anchorage.  —  At  least  one  end  of  every  bridge  must  be 
anchored  to  the  foundations.  If  the  overturning  moment  of 
the  greatest  assumed  wind  pressure  be  more  than  half  the 
resisting  moment  of  the  weight  of  the  bridge,  the  latter  must 
be  anchored  at  the  roller  end  also,  but  in  such  a  manner  as  not 
to  interfere  with  the  expansion. 

Sliding.  —  At  the  roller  end  of  a  bridge,  if  the  frictional 
resistance  to  the  sliding  of  the  shoe  in  the  direction  of  the  axes 
of  the  rollers  be  not  more  than  double  the  tendency  to  slide 
produced  by  the  wind  pressure,  a  resistance  equal  to  the  differ- 
ence between  this  tendency  and  the  frictional  resistance  with  a 
factor  of  safety  of  four  (4)  must  be  provided. 


ORDINARY  IRON  HIGHWAY-BRIDGES.  g 

CiHitii/iioiis  Sfaiis.  —  Except  in  the  case  of  swing  bridges  or 
cantilevers,  consecutive  spans  are  not  to  be  made  continuous 
■over  the  points  of  support. 

Camber.  —  The  cambers  for  bridges  of  the  different  spans  are 
to  be  taken  from  the  following  table  :  — 


Si'AN  IN  Feet. 

Camber  in  Inches. 

Si'AN  IN  Feet. 

Camber  in  Inches. 

40-60 

I.O 

180-220 

3-S 

60-80 

'S 

220-250 

4.0 

,So-ioo 

2.0 

250-280 

4-5 

100-140 

2.5 

280-300 

5.0 

1 40- 1  So 

3-0 

Vertical  Sway  Bracing.  — \n  all  deck  bridges,  and  in  all 
through  bridges  where  the  depth  from  centre  to  centre  of 
chords  is  twenty-four  (24)  feet  or  over,  vertical  sway  bracing 
is  to  be  used. 

Portal  and  Lateral  Struts.  —  Portal  and  lateral  struts  are  to 
be  proportioned  to  resist  the  compression  produced  by  the 
wind  pressure  and  the  initial  tensions  in  all  the  rods  meeting  at 
the  end  of  the  strut.  If  the  strut  be  also  subjected  to  bending, 
then  to  the  area  necessary  to  resist  compression  must  be  added 
sufficient  area  to  resist  the  bending ;  the  intensity  of  working 
bending-stress  being  taken  equal  to  six  (6)  tons. 

Effect  of  Wind  on  Posts  and  Batter  Braces.  —  But  the  effect 
of  the  wind  on  the  posts  and  batter  braces  is  not  to  be  considered 
to  occur  when  the  bridge  is  fully  loaded  :  so,  unless  the  stresses 
produced  thereby  exceed  the  product  of  the  live  load  stresses 
by  the  ratio  of  seven  and  a  half  (7.5)  to  the  intensity  of  working 
tensile  stress  for  the  bottom  chord,  the  effect  of  the  wind  on 
these  members  may  be  neglected. 

Effect  of  Wind  Pressure  on  Bottom  Chord  Tension.  —  For  the 
same  reason,  the  sectional  area  of  the  bottom  chord  need  not 
be  increased  to  resist  the  tension  caused  by  the  wind,  unless 
the  latter  exceed  the  product  of  the  live  load  stress  by  the  ratio 
of  seven  and  a  half  (7.5)  to  the  intensity  of  working  tensile 
stress  for  chord  bars. 


10 


ORDIXARY  IRON  HIGHU'A  Y-li RIDGES. 


Initial  Tension.  —  To  allow  for  the  stresses  caused  in  adjusta- 
ble members  by  the  screwing  up  of  the  turn  buckles  or  sleeve 
nuts,  the  stress  in  each  such  member  is  to  be  increased  by  the 


amount  given  in  the  following  table  :■ 


iMA.MiniCU    (IK    Kl>I>. 

Inhial   Tension. 

DlAMETKR   (IK    R(ll). 

Initiai,  'Iensiiin, 

1" 

0.50  ton 

■1" 

2.25  tons 

r 

0.75  ton 

If 

2.50  tons 

I" 

1. 00  ton 

•r 

2.75  tons 

li" 

1.25  ton 

2" 

3.00  Ions 

li" 

1.50  ton 

^-^' 

3.25  tons 

If" 

1.75  ton 

2f' 

3.50  tons 

li" 

2.00  tons 

2a" 

375  t<"i^ 

Square  or  flat  bars  are  to  receive  the  allowance  for  round  rods 
of  equal  sectional  area. 

Conncctioti  for  Lateral  Systems. — Whenever  it  be  possible, 
the  lateral  rods  of  both  upper  and  lower  systems  are  to  be 
connected  directly  to  the  chord  pins.  But,  if  the  rods  exceed 
one  and  three-quarter  (i|)  inches  in  diameter,  bent  eyes  are  not 
to  be  employed. 

Lower  lateral  rods  are  not  to  be  attached  to  the  floor  beams. 
To  make  them  clear  the  joists,  wooden  lateral  struts  resting 
on  the  floor  beams,  and  having  wrought-iron  jaws  at  their  ends 
attached  to  the  chord  pins,  are  to  be  employed  for  the  joists  to 
rest  upon. 

These  wooden  struts  are  to  be  bolted  about  every  two  feet 
through  the  upper  flange  of  the  floor  beam  by  five-eighth  {\) 
inch  bolts,  care  being  taken  to  stagger  the  bolt  holes,  and  to 
avoid  placing  a  bolt  at  the  middle  of  the  beam. 

Should  the  sizes  of  the  lateral  rods  be  such  as  to  prevent  the 
use  of  bent  eyes,  pins  dropped  vertically  through  the  jaws  are 
to  be  employed. 

Stresses  in  End  Lower  Lateral  Stmts.  —  In  figuring  the  stress 
in  a  lower  lateral  strut  at  the  roller  end  of  a  l^ridge,  the 
stress  caused  by  the  wind  pressure  is  to  be  added  to  the  trans- 
verse component  of  the  initial  tension  in  the  end  lateral  rod. 


ORDINARY  IRON  HIGHIVAV-URIDGES. 


I  I 


lAI. 

'i'ENSlON. 

25 

tons 

50 

Ions 

75 

tons 

00 

tons 

-5 

tons 

50 

tons 

75 

tons 

round  rods 


ai.d  Irom  the  sum  is  to  be  subtracted  the  product  of  the  press- 
lire  on  the  windward  shoe,  when  the  bridge  is  empty  and  sub- 
jected to  the  greatest  wind  pressure,  l)y  the  co-efficient  of  iron 
upon  iron,  which  is  about  0.25  for  this  case. 

Stiffened  End  Panels.  ~\l,  in  the  end  panel  of  a  bridge,  the 
longitudinal  component  of  the  greatest  allowable  working^stress 
(including  initial  tension)  in  the  lower  lateral  rod  exceed  the 
tension  in  the  lower  chord  of  that  panel,  caused  by  the  dead 
load  alone,  when  the  bridge  is  subjected  to  the  greatest  wind 
p--jssure,  the  bottom  chord  of  that  panel  must  be  made  to  resist 
both  tension  and  the  excess  of  compression.  Where  two  chan- 
nels are  employed  for  the  lower  chord  section,  the  effective  area 
of  tie  webs  alone  must  be  counted  on  to  resist  tension.  Where 
the  sriffening  is  obtained  by  trussing  the  inner  chord  bars,  the 
intensities  of  working  tensile  stress  to  be  employed  for  the  net 
section  of  those  bars  arc  four  (4)  tons  for  bridges  of  Class  A, 
and  five  (5)  tons  for  those  of  Classes  B  and  C. 

Top-Chord  and  Battcr-Bracc  Sections.  —  The  top  chords  and 
batter  braces  shall  consist  of  two  channels,  with  a  plate  above, 
and  latticing  or  lacing  below.  The  top  plate  must  be  of  the 
same  section,  and  the  chord  channels  of  the  same  depth,  from 
end  to  end  of  span  ;  the  increase  in  chord  section  towards  the 
middle  being  ojjtained  by  thickening  the  webs  of  the  chan- 
nels. 

Post  5<v7/,vAv.  —  Posts  arc  to  consist  of  two  channels,  with 
latticing  or  lacing  on  each  side.  The  upper  ends  may  be  either 
rigidly  attached  to  the  chords,  or  may  be  hinged  on  the  pins ; 
preference  being  given  to  the  latter  method. 

Portal  and  Upper  Lateral  Stmt  Seetions.  —  Portal  struts  anrl 
upper  lateral  struts  are  to  be  formed  of  two  channels,  latticed  o-- 
laced,  and  rigidly  attached  at  their  ends  to  the  batter  braces  or 
chords. 

IVorkin^^r  Tensile  5/;r...r.x  -  Except  for  the  case  of  trussed 
bars,  mentioned  under  the  divisions  "  Stiffened  I-:nd  Panels  "  and 
"Stiffened  Hip  Verticals,"  the  intensities  of  working-strosses  for 
iron  in  tension  in  the  various  members  are  to  be  as  given  in  the 
f'.>llowing  table :  — 


ORDLXARV  IRON  HliiH WAY-BRIDGES. 


MEMBERS. 


Lower  chord  bars  and  end  main  diagonals  . 
Middle  panel  diagonals,  counters,  and  hip 

verticals 

Flanges  of  rolled  beams 

Flanges  of  built  beams  (net  section)    .     .     . 

Lateral  and  vibration  rods 

Beam-hangers 


Intensitiks  i)F  W'okkinc.-Strkss. 


Class  A.  Classes  B  and  C. 


5.00  tons 

4.00  tons 
5.00  tons 
4.00  tons 
7.50  tons 
3.00  tons 


6,25  tons 

5.00  tons 
6.00  tons 
5.00  tons 
7.50  tons 
4.00  Lons 


The  intensities  of  working-stress  for  main  diagonals  inter- 
mediate between  the  counters  or  middle  panel  diagonals  and 
the  end  diagonals  lie  between  four  (4)  and  five  (5)  tons  for 
bridges  of  Class  A,  and  between  five  (5)  and  six  and  a  quarter 
(6|)  tons  for  those  of  Classes  B  and  C;  the  amounts  being 
directly  interpolated  according  to  the  position  of  the  panel. 

Working  Compressive  Stresses.  —  For  struts  composed  of  two 
channels  with  plates,  or  lacing,  or  latticing,  the  following  for- 
mulas are  to  be  used  in  finding  the  intensities  of  working 
compressive  stresses. 

For  chords,  batter  braces,  and  posts  in  bridges  of  Class  A, 

/ 


I  + 


H^ 


P  = 


4  + 


20 


and  for  all  other  cases, 


/ 


1  + 


/  = 


4  + 


C 


30 


H  = 


p  being  the  intensity  of  working-stress,  and 
length  of  strut 
least  diameter  of  stmt' 
f  19.25  for  two  fixed  ends 

(1  end  and  one  hinged  end 
.yo  • 


/=  I  19.25  for  one  fixed  end  and 
I  18.90  for  t\\(i  liin:j:cil  rnds, 


OND/X.IKV  nWN  HlGHWAY-liRlDGES. 


13 


'iiukinc-Stress. 

Classes  B  and  C. 

6.25  tons 

5.00  tons 

6.00  tons 

5.00  tons 

7.50  tons 

4.00  ions 

and 

[5820  for  two  fixed  ends. 
C  -■-  \  3000  for  one  fixed  end  and  one  hinged  end 
[  1900  for  two  hingctl  ends. 

Where  I-beams  are  employed  for  intermediate  struts  or  end 
lower  lateral  struts,  the  working-stresses  arc  to  be  taken  from 
Table  XL.  For  the  flanges  of  rolled  beams,  the  intensities  of 
working  compressive  stress  are  to  be  taken  equal  to  five  (5)  tons 
for  bridges  of  Class  A,  and  six  (6)  tons  for  bridges  of  Classes  H 
and  C.  For  the  flanges  of  built  beams,  the  corresponding  inten- 
sities are  to  be  four  (4)  and  five  (5)  tons  respectively  on  the 
gross  section. 

Working  Bcnding-Strcsscs.  —  The  intensities  of  working  bcnd- 
ing-stress  on  pins  arc  to  be  seven  and  a  half  (7.])  tons  for  bridges 
of  Class  A,  and  nine  and  three-eighths  (9|)  tons  for  those  of 
Classes  B  and  C.  For  pins  belonging  wholly  to  the  lateral 
systems  of  bridges  of  either  class,  the  intensity  of  working 
bending-stress  may  be  taken  equal  to  eleven  and  a  quarter 
(I  i|)  tons.  The  intensities  of  working  bending-stress  for  rivets 
are  to  be  seven  and  a  half  (7.])  tons  for  bridges  of  Class  A,  and 
nine  and  three-eighths  (9'^)  tons  for  those  of  Classes  V>  and  C. 
The  latter  intensity  is  also  to  be  used  for  the  lateral  systems  of 
bridges  of  Class  A. 

Where  steel  pins  are  employed,  the  intensity  of  working 
bending-stress  must  not  be  taken  greater  than  twelve  (12)  tons 
for  bridges  of  Class  A,  or  fifteen  (15)  tons  for  those  of  Classes 
B  and  C,  unless  special  experiments  on  the  steel  used  show  an 
ultimate  bending  resistance  greater  than  si.xty  (60)  tons  per 
sc|u:He  inch  ;  in  which  case  a  factor  of  five  (5)  may  be  used  for 
bridges  of  Class  A,  and  a  factor  of  four  (4)  for  those  of  Classes 
B  and  C.  As  before  stated,  the  intensity  of  working  bending- 
stress  for  channels  in  portal  and  lateral  struts  is  to  be  six  (6) 
tons. 

Working  Bcaring-Strcsscs.  —  The  intensities  of  working  bear- 
ing-stress for  pins  and  rivets,  measured  upon  the  projection  of 
the  semi-intrados  upon  a  diametral  plane,  are  to  be  six  (6)  tons 
for  bridges  of  Class  A,  and  seven  and  a  half  (7.^)  tons  for  those 


'4 


ORD/XARV  /ROX   Hh'.IIWA  V-liRllh'.ES. 


of  Classes  V>  and  C.  I'or  pins  and  rivets  belonging;  wholly  to 
the  lateral  system  of  a  bridge  of  any  class,  the  intensity  is  to 
be  taken  equal  to  seven  an'l  a  half  (7^)  tons. 

Sirjcs  of  rp/'cr  Lntrnil  Rods. — In  bridges  of  less  than  two 
hundred  {200)  feet  span,  the  stresses  in  the  upper  lateral  system 
in  through  bridges,  or  the  lower  lateral  system  in  deck  bridges, 
usually  call  for  sections  of  rods  which  are  practically  too  small : 
therefore  the  inferior  limits  of  the  diameters  of  these  rods  in 
such  cases  are  to  be  taken  from  Table  XXV. 

Stiffened  Hip  W-rticah.  —  Hip  verticals  in  three  or  four  panel 
pony  trusses  are  to  be  stiffened  so  as  to  resist  compression.  If 
the  section  employeil  consists  of  two  channels,  the  net  section 
of  the  webs  alone  is  to  be  relied  on  to  resist  tension.  If  it  con- 
sists of  two  flat  bars  trussed,  the  intensities  of  working  tensile 
stress  on  the  net  section  are  to  be  reduced  to  three  (3)  tons  for 
bridges  of  Class  A,  and  to  four  (4)  tons  for  those  of  Classes  H 
and  C. 

Trussing.  — Trussing  is  to  be  used  only  in  the  posts  of  pony 
trusses,  where  there  is  a  great  excess  of  strength,  in  the  hip 
verticals  of  pony  trusses,  and  in  stiffening  lower  chord  bars. 

Upset  Ends.  —  Middle  panel  diagonals,  counters,  lateral  rods, 
vibration  rods,  and  all  other  adjustable  rods,  excepting  beam 
hangers  that  have  an  excess  of  section,  are  to  have  their  ends 
enlarged  for  the  screw  threads,  so  that  the  diameter  at  the  bot- 
tom of  the  thread  shall  be  one-si.xteenth  (,";.)  of  an  inch  greater 
than  that  of  the  body  of  the  rod,  .square  or  Hat  bars  being 
figured  as  if  of  equivalent  round  section. 

Threads. — All  threads,  except  those  on  the  ends  of  pins, 
must  be  of  the  United-States  standard. 

Miiiininin  Dimensions  of  Chord  and  Batter-Brace  Plates.  — 
The  minimum  dimensions  for  the  top  plate  in  top  chords  and 
batter  braces  are  to  be  taken  from  the  following  table.  For  five 
(5)  and  six  (6)  inch  channels,  the  thickness  docs  not  increase 
with  the  width.  For  seven  (7)  inch  channels,  the  thickness 
should  be  increased  to  five-sixteenths  (/',.)  of  an  inch,  should 
the  width  exceed  fifteen  (15)  inches.  For  the  other  channels, 
should  the  width  of  plate  exceed  that  given  in  the  table  by 
from  forty  (40)  to  seventy  (70)  per  cent,  the  thickness  must  be 


s  than  two 
cral  system 
ick  bri(l};es, 
,'  too  small : 
jsc  rods  ill 


;inf;  tensile 


bars   bein<^ 


ONJJ/XANV  /h-OX  umilWA  Y-liRinCES. 


IS 


Increased  by  one-sixteenth  (j\,)  of  an  inch,  while,  if  it  exceed 
by  more  than  seventy  (70)  per  cent,  the  thickness  must  be 
iiuToased  by  one-eighth  (J)  of  an  inch. 


Iii-rni  i)K 

MiNIMlM 

MlNIMI'M 

l)i:nii  (IP 

MiM.MI'M 

MiNlMIM 

ClIANNBL. 

s" 

Thickness. 

Width. 

Channel. 

Thickness, 

WlDlll, 

f 

7" 

9" 

A" 

\\\" 

6" 

f 

8" 

10" 

A" 

I2V' 

7" 

f 

9" 

12" 

i" 

IS" 

,S" 

i" 

10" 

15" 

i" 

■  9" 

AAn' /'/-^Ax —Sizes    of  stay  plates   are    to    be    taken    f 


rom 


Tables  XXXII.  and  XXXIII.  Stay  plates  on  latticed  or  laced 
compression  members  are  to  be  i)laced  as  near  the  pin  holes  as 
possible.  Latticing  or  lacing  must  never  be  used  without  stay 
plates  at  the  ends. 

I.atticiiii:;  (vui  Laciiio;  Inirs.  —  The  sizes  for  lattice  bars  and 
lacing  bars  are  to  be  taken  from  Tables  XXX.  and  XXXI. 
The  distance  from  the  back  of  an  end  rivet  hole  to  the  end 
of  the  bar  must  not  be  less  than  one-half  the  width  of  the  bar. 
The  ends  of  the  bars  are  to  be  semicircular,  except  when  there 
are  two  rivets  at  each  end,  in  which  case  they  should  be  cut 
l)arallel  to  the  channels. 

Inclination  of  Latticiiii^  and  Lacing  Bars.  —  Lattice  bars  shall 

ces  will  permit. 


make  with  each  other,  as  nearly  as  circumstan 
angles  of  ninety  (90)  degrees ;  and  lacing  ba 


rs,  an<iles 


of 


SIX 


(60)  degrees. 


ty 


Diameters  of  Rivets  for  Different  Channels.  —  For  attaching 
|)lates  and  Ltttice  or  lacl.-.g  bars  to  the  flanges  of  channels,  the 
least  diameters  of  the  rivets  to  be  used  are  to  be  taken  from 
the  following  table  ;  and  the  greatest  diameters  must  not  exceed 
those  there  given  by  more  than  one-eighth  (J)  of  an  inch. 


Drptli  of  tliiinnel     .     .     4"      5" 
Di.imuter  of  rivets  .     ,     4"      J" 

6" 
k" 

7" 
9  " 

V6 

8" 
1" 

9" 

10"      12" 

11"         3" 
16        1      % 

15" 

13" 
16 

Splice  Plates.— The  length  of  a  splice  plate  is  to  be  deter- 


16 


oRP/x.ih']'  /A'o.v  nhiiiW'A  v-nh'/in;/:.s\ 


mined  by  the  niinihcr  of  rivets  necessary  to  transfer  the  stress 
from  one  main  meniber  to  the  other.  The  sum  of  the  workinj; 
bearing  resistances  of  all  the  rivets  on  either  side  of  the  joint 
must  not  be  less  than  the  stress  in  the  main  member  upon  that 
side.  The  rivets  must  also  be  fi^an-ed  for  beiulin};.  When 
practicable,  a  splice  plate  must  be  placed  on  each  side  of  every 
member  where  a  joint  occurs. 

The  transmission  of  compressive  stresses  shall  be  considered 
as  entirely  throu^di  the  medium  of  the  rivets  and  connectin^^ 
plates,  and  these  must  be  proportioned  accor(lin<;ly ;  so  that  the 
area  of  the  two  sj^lice  plates  connecting  two  channel  bars  must 
be  at  least  ecpial  to  that  of  the  Iar},^er  channel  bar. 

Ki-i/z/o/rn/^i,'-  J'^latis.  —  Simple  re-enforcing  plates,  or  plates 
riveted  to  webs  at  pin  holes  in  order  to  compensate  for  strength 
lost  there,  or  to  provide  additional  bearing  for  the  pins,  must 
have  as  many  rivets  to  attach  tliem  to  the  webs  as  will  give 
bearing  and  bending  resistances  for  the  same,  equivalent  to  at 
least  the  greatest  stresses  that  can  come  upon  the  re-enforcing 
plates. 

Cover  Plates.  —  Cover  plates  for  top  chords  or  batter  braces 
are  to  have  the  same  section  as  the  chord  or  batter-brace  |)late, 
the  joints  in  which  they  cover,  and  enough  rivets  on  each  side 
of  the  joint  to  take  up  the  greatest  stress  that  could  ever  come 
U|)on  the  said  chord  or  batter-brace  plate. 

Extension  Plates.  —  Ivxtension  plates  on  the  end  of  a  strut, 
for  the  purpose  of  hinging  the  latter,  are  to  have  at  least  twice 
the  sectional  area  of  the  strut  from  the  pin-hole  to  the  nearest 
edge  of  the  stay  jilate  ;  and  the  thickness  must  be  great  enough 
to  give  sufficient  bearing  upon  the  pin.  The  length  of  the 
extension  plates  is  to  be  such  as  to  allow  of  the  use  of  a  suffi- 
cient number  of  rivets  to  provide  proper  bearing  and  bending 
resistances  for  the  same. 

Shoe  Plates,  Roller  Plates,  ami  Bed  Plates.  —  No  shoe  jilate 
is  to  have  a  less  thickness  than  three-cpiarters  {\)  of  an  inch, 
and  no  roller  plate  or  bed  plate  a  less  thickness  than  seven- 
eighths  (^)  of  an  incli.  When  nine  (9)  or  ten  (10)  inch  chan- 
nels are  used  for  tlie  batter  braces,  the  thickness  of  the  shoe 
plates  is  to  be  seven-eighths  {\)  of  an  inch.     When  twelve  (12) 


r)A7>/.\. //T  fNOX  mcinVAV-nNlDC.KS. 


17 


considered 


iiuli  rlKinm-ls  are  used  for  tlie  l)atter  braces,  the  thickness  of 
the  slioe  plates,  roller  plates,  and  bed  plates,  is  to  be  one  (i) 
iiuh  ;  and,  when  fifteen  (15)  inch  channels  arc  used,  it  is  to  be 
(Hie  :'nd  an  eighth  {\\)  inches. 

Ik'd  plates  must  be  of  such  dimensions  that  the  fjreatcst 
pressure  on  the  masonry  shall  not  exceed  two  hun.Ired  (200) 
pounds  per  scpiare  inch. 

Every  bearinj;  upon  masonry  must  lie  provided  with  cither  a 
bed  plate  or  a  roller  plate,  well  fastened  to  the  masonry  by  bolts 
not  less  than  one  (1)  inch  in  diameter;  but,  if  the  shoe  plate 
i)e  sufficiently  large,  it  may  act  as  a  bed  plate  at  the  fixed  i^mX 
(if  tile  span. 

Inam-llaiii^ir  Plates.  —  Ream-hanger  plates  arc  never  to  be 
made  less  than  three-(piarters  {%)  of  an  inch  thick,  and  their 
ru-eas  are  to  be  such  that  the  hanger  nuts  will  always  have  a  full 
bearing  thereon.  The  necessary  thickness  for  a  beam-han-er 
plate  is  to  he  determined  by  considering  it  as  a  beam  uniformly 
loaded  by  the  whole  weight  that  comes  on  th,.  luingers  ;  the 
length  of  said  beam  being  the  distance  between  the  centres  of 
the  holes  through  whieh  pass  the  ends  of  one  hanger,  and  its 
width  I)eing  the  extreme  dimension  of  the  plate,  mc^isured  par 
allel  to  the  floor  beam.  The  intensity  of  working-stress  for 
ben.hng  in  the  plate  is  to  be  taken  equal  to  that  used  in  pro- 
portioning  the  lloor  beam. 

Rivctii,}^r,  _  In  ri,,ctcd  work,  all  joints  arc  to  be  squarely  and 
truly  dressed,  and  the  rivet  holes  must  be  accurately  spaced 

No  rivets  with  crooked  heads,  or  heads  not  formed  accurately 
on  the  shank,  or  rivets  which  are  loo.se  either  in  the  rivet  holes 
or  under  the  shoulders,  will  be  allowed  in  a  bridge. 

Kivet  holes  in  top-chord  plates  and  batter-brace  plates  shall 
be  spaced  as  nearly  as  practicable  two  and  a  half  (2I)  inches 
eenlre  to  centre  near  the  panel  points,  and  four  (4)  inches  centre 
to  centre  elsewhere. 

No  rivet-hole  centre  shall  be  less  than  one  and  a  half  (lU 
<  lameters  from  the  edge  of  a  plate:  whenever  practicable,  this 
distance  is  to  be  increased  to  two  (2)  diameters. 

The  diameter  of  a  hole  shall  never  exceed  that  of  the  rivet  by 
more  than  one-sixteenth  {-^)  of  an  inch. 


i8 


OA'/)/A:iA'r   /A'O.V  IIlCUWAV-nRlDGES. 


When  two  or  more  thicknesses  of  plate  are  riveted  together 
in  compression  memljers,  the  outer  row  of  rivets  shall  not  be 
more  than  three  (3)  diameters  from  the  side  edge  of  the  plate. 

Rivet  holes  must  never  be  spaced  less  than  two  and  a  haif 
(2},)  diameters  from  centre  to  centre:  it  is  preferable  that  this 
distance  be  increased  to  three  (3)  diameters  when  so  doing  will 
not  cause  inconvenience  in  designing. 

All  the  rivet  holes  of  the  respective  parts  of  any  structure 
must  be  made  to  exactly  coincide,  either  b>  drilling  the  holes 
full  size  through  the  connecting  portions,  after  being  put 
together,  or  by  sub-punching  the  pieces  separately,  and  after- 
wards reaming  the  combined  rivet  holes  to  proper  size.  In  all 
cases  the  burrs  must  be  removed  by  slightly  countersinking  the 
edges  of  the  holes. 

All  rivets  in  splice  or  tension  joints  are  to  be  systemati- 
cally arranged,  so  that  each  half  of  a  tension  member  or  splice 
plate  will  have  the  same  uncut  area  on  each  side  of  its  centre 

line. 

No  rivet,  excepting  those  in  shoe  plates,  is  to  have  a  less 
diameter  than  the  thickness  of  the  thickest  plate  through  which 
it  passes,  nor  in  any  case  less  than  half  (\)  an  inch. 

Built  J/rw/v/x  —  The  several  pieces  forming  one  built  mem- 
ber must  fit  closely  together,  and  when  riveted  shall  be  free 
from  twists,  bends,  or  open  joints. 

Use  of  Balis.— Ihc  use  of  bolts  instead  of  rivets  is  to  be 
avoided  whenever  practicable. 

Lateral  Dracin^r  for  Plate  Girders.  —When  a  span  consisting 
of  plate  girders  is  over  fifteen  (15)  feet  in  length,  the  adjacent 
girders  are  to  be  braced  to  each  other  by  diagonal  angle  irons 
attached  to  or  near  the  lower  flanges.  There  are  to  be,  also, 
light  bracing-frames  at  each  end  between  adjacent  girders,  so 
placed  as  not  to  interfere  with  the  expansion.  When  the  si^an 
is  over  twenty-five  (25)  feet  in  length,  the  upper  flanges  of 
adjacent  girders  are  also  to  be  connected  by  diagonal  angle-iron 

braces. 

In  every  case  the  joists  are  to  be  dapped  at  least  an  inch 
onto  the  girders,  and  every  third  joist  resting  on  any  girder  is 
to  be  bolted  through  the  upper  flange. 


ORD/AARV  IROX  HlGHlVAY-nRlDGES. 


19 


Fonna/a  jor  Built  Floor  Bavus  mid  Plate  Girders  * —  The 
tension  flanges  of  built  floor  beams  and  plate  girders  are  to  be 
proportioned  by  the  formula 


A  = 


8DT      6 


+  A", 


where  A  is  the  area  of  the  flange,  A'  that  of  the  web,  A"  that 
lost  from  the  flange  by  a  rivet  hole,  JFthe  uniformly  distributed 
load  in  tons,  /.  the  length  of  the  beam  in  feet  betv  jen  centres 
of  supjjorts,  7)  the  depth  in  feet  between  centres  of  gravity  (,( 
flanges,  and  T  the  intensity  of  working  tensile  stress  in  tons. 
The  same  formula  will  apply  to  the  compression  flanges  by 
making  A"  equal  to  zero. 

Stiffnnrs.  —  Built  floor  beams  and  plate  girders  must  be  stiff- 
ened by  four  (4)  angle  irons  at  each  support,  and  by  two  (2) 
angle-irons  at  several  intermediate  points  ;  the  distance  apart 
of  the  stiffeners  being  made  no  greater  than  twice  the  depth  of 
the  beam  when  the  ratio  of  thickness  of  web  to  depth  of  same 
is  not  less  than  one-eightieth  {^^),  and  no  greater  than  one  and 
a  half  (I J)  times  the  depth  when  this  ratio  is  one  over  one 
hundred  and  twenty  (y-|^).  Distances  for  intermediate  ratios 
arc  to  be  interpolated. 

Tee-irons  are  not  to  be  used  as  stiffeners. 

Stiffening  angles,  which  must  always  be  in  pairs  (one  angle 
on  each  side  of  the  web),  must  extend  from  the  upper  leg^'of 
the  upper  flange  angle  to  the  lower  leg  of  the  lower  fla^nge 
angle,  being  made  flush  with  the  other  legs  of  the  flanges  by 
filling  plates. 

U'r/>  Splices  in  Floor  Beams  and  Plate  Girders.  — Wchs  of 
floor  beams  and  plate  girders  must  be  well  spliced  at  all  joints 
by  a  splice  plate  on  each  side  of  the  web  ;  and  joints  must  be 
located  where  the  shear  is  not  great. 

Limitiug  Depths  of  Floor  Beams  and  Plate  Girders.  —  The 
depth  of  the  web  of  a  floor  beam  or  plate  girder  must  never 
exceed  one  hundred  and  twenty  (120)  times  its  thickness. 


•  For  proof  of  this  formula,  see  Appendix  II. 


20 


ORDLXARV  IROX  HIGHWAY-BRIDGES. 


Rivets  in  Flanges  of  Floor  Bcmiis  and  Plate  Girders.  —  In 
spacing  the  rivets  in  the  flanges  of  floor  beams  and  plate  gird- 
ers, the  flanges  are  to  be  divided  into  portions  of  about  two  (2) 
feet  in  length,  the  stresses  in  the  flanges  are  to  be  found  at 
each  point  of  division,  and  there  must  be  enough  rivets  between 
any  consecutive  points  of  division  to  take  up  the  dilfercnce 
between  the  stresses  at  the  points,  providing  that  the  rivets  be 
not  spaced  more  closely  than  two  and  a  half  (2i)  diameters, 
nor  more  than  six  (6)  inches  apat. 

/y,,x  _In  welded  heads,  the  length  of  metal  behind  the  pni- 
hole  must  be  at  least  equal  to  the  depth  of  the  bar  or  diameter 
of  pin,  whichever  be  the  greater,  unless  the  head  be  corre- 
spondingly thickened  ;  while  in  hammered  heads  the  amount  is 
to  be  the  same  as  that  above  or  below  the  pin  hole. 

The  least  amount  of  metal  in  the  heads  across  the  pin  holes 
is  to  be  as  given  in  the  following  table  :  — 


DIAMETER  OF  I'lN 

Metal  in  Head  across  Pin. 

WIDTH  OF  BAR 

Welded. 

Hamnicred. 

o.So 

1.50 

1.50 

1.04 

1.50 

1.50 

1. 12 

1.50 

I-S3 

1.20 

1.50 

,.56 

1.28 

1.50 

1.60 

1.36 

1-55 

1.72 

143 

1 .60 

1.76 

1.50 

1.67 

1.85 

1.64 

i.r,7 

1-95 

177 

1.70 

2.05 

1.90 

..76 

'Til 

In  loop  eyes  the  distance  of  the  inner  point  of  the  loop  from 
the  centre  of  the  pin  must  not  be  less  than  three  (3)  times  the 
diameter  of  the  pin.  The  loop  must  fit  closely  to  the  pin 
throughout  its  semi-circumference. 

Pin  holes  in  eye  bars  shall  be  bored  to  an  exact  size  and  dis- 
tance, and  to  a  true  perpendicular  to  the  line  of  stress.  No 
error  in  the  length  of  bar  exceeding  one  sixty-fourth  (,.'4)  of  an 


ORDINARY  IRON  II IGIIW AY-BRIDGES. 


21 


irdcrs.  —  In 
I  plate  <;-ird- 
bout  two  (2) 
be  found  at 
/ets  between 
e  (lilference 
he  rivets  be 
)  diameters, 

lind  tlie  pin- 

or  diameter 

id   be   eorre- 

le  amount  is 

he  pin  holes 


mc 


h  will  be  allowed,  nor 


ROSS  Pin. 


Hammered. 


1.50 
1.50 

'•S3 
1.56 
1.60 
1.72 
1.76 
1.8s 
1.9s 
2.05 
2.21 


the  loop  from 

(3)  times  the 

<f  to   the    pin 

size  and  dis- 
f  stress.  No 
irth  (ji'^)  of  an 


# 


J  variation  of  more  than  one  thirty- 
secon.d  {^.,)  of  an  inch  between  the  centre  of  the  eye  and  the 
centre  line  of  the  bar. 

J'iiis.  —  Pins  are  to  be  proportioned  to  resist  the  greatest 
bending  produced  in  them  by  the  bars  or  struts  which  they 
connect. 

Steel  pins  are  also  to  be  proportioned  for  shearing. 

No  pin  is  to  have  a  diameter  less  than  eight-tenths  {-^^)  of 
the  depth  of  the  deepest  bar  coupled  thereon  ;  nor  shall  it  vary 
from  that  of  the  eyes  of  the  bars  coupled  theretc  by  more  than 
one-fiftieth  (r,^,)  of  an  inch. 

The  least  allowable  diameters  for  chord  pins  are  two  (2) 
inches  for  bridges  of  Class  A,  and  one  and  a  half  {\l)  inches 
for  those  of  Classes  B  and  C.  The  least  allowable  diameter  for 
pins  belonging  wholly  to  the  lateral  systems  of  bridges  of  any 
class  is  one  and  a  quarter  {\\)  inches. 

J'iii  Baviiigs.— AW  pin  holes  through  webs  shall  be  re-en- 
forced by  additional  material,  so  that  the  permissible  pressure 
upon  the  bearings  shall  not  be  exceeded.  Where  a  pin  bears 
against  a  re-enforced  channel  bar,  the  web  of  the  latter  is  not  to 
be  assumed  to  take  any  bearing-stress,  unless  the  re-enforcing 
plates  be  riveted  to  it  before  the  pin-hole  be  bored. 

Chord  I\ickii/o^. — The  lower  chords  are  to  be  packed  as 
closely  as  possible,  and  in  such  a  manner  as  to  produce  the 
least  bending-moments  upon  the  pins.  The  various  members 
attached  to  any  pin  must  be  packed  as  closely  as  possible,  and 
all  interior  vacant  spaces  must  be  filled  with  wrought-iron 
fillers. 

Rxpaitsion  Rollers.  —  Expansion  rollers  for  bridges  of  Class  A 
are  to  be  proportioned  by  the  formula 

/  =  0.25^^7, 
and  those  for  bridges  of  Classes  B  and  C  by  the  formula 

/  =  o.3i25V'^, 

where  p  is  the  working-load  in  tons  per  lineal  inch  of  roller,  and 
d  is  the  diameter  of  the  roller  in  inches. 


22 


OKD/XAKV  /h'OX   IIICinVA  V-IIK/IHUCS. 


The  least  allowable  diameters  for  rollers  are  one  and  three- 
quarters  (\\)  inches  for  bridges  of  Class  A,  and  one  and  a  half 
(I  1)  inches  for  bridges  of  Classes  H  and  C.  The  spaces  between 
roflers  must  ne^■er  exceed  three-quarters  (|)  of  their  diameter. 

Ttini  niickhs  iiiid  Slave  Nuts.  —  All  turn  buckles  and  sleeve 
nuts  must  be  made  so  strong,  that  they  will  be  able  to  resist 
without  rupture  the  ultimate  pull  of  the  bars  which  they  con- 
nect, and  without  distortion,  the  greatest  twisting-force  to  which 
they  could  ever  be  subjected.  U-nuts  are  not  to  be  used  in  any 
part  of  a  bridge. 

Sizes  of  Xiits.  —  The  dimensions  of  all  scpiare  and  hexagonal 
nuts  for  the  various  diameters  of  rods  are  to  be  taken  from 
Carnegie's  "Pocket-Companion"  (pp.  130,  13  1),  excepting  those 
nuts  on  the  ends  of  pins  which  are  subject  to  but  a  slight  ten- 
dency to  sheir  the  thread  :  in  this  case,  these  dimensions  may 
be  diminished,  in  direct  [iroportion  to  this  tendency,  until  the 
thickness  reaches  the  limit  of  one-half  (i)  of  an  inch. 

Washers  ami  Xiits.  —  Washers  and  nuts  must  have  a  uniform 
bearing.  Cast-iron  washers  must  be  used  under  the  heads  and 
nuts  of  all  timber  bolts,  when  the  bearing  is  on  the  wood. 

Beam  Ilai/oers.  —  Whenever  possible,  four  (4)  beam  hangers 
per  beam  are  to  be  used.  The  screw  ends  are  to  be  provided 
with  check  nuts. 

y^,j,y.  _  Great  care  must  be  taken,  ii  designing  jaws  for  the 
ends  of  any  strut,  that  they  be  so  strong  in  every  respect,  that, 
when  the  strut  is  subjected  to  its  ultimate  load,  it  will  fail  near 
the  middle  rather  than  at  the  ends. 

Bnnkets.  —  Brackets,  or  knees,  must  be  used  to  connect  each 
overhead  strut  to  the  posts  or  batter  braces.  They  should  be  of 
straight  tee,  angle,  or  channel  iron  :  if  made  curved,  no  depend- 
ence is  to  be  placed  upon  them,  either  for  strength  or  stiffness. 
When  there  is  no  vertical  sway  bracing,  each  intermediate 
bracket  must  be  proportioned  to  resist  the  compression  induced 
in  it  by  the  wind  pressure  concentrated  at  the  windward  and  lee- 
ward points  of  that  panel  of  the  top  chords  to  which  the  bracket 
belongs;  and  each  portal  bracket,  to  resist  the  compression 
induced  in  it  by  one-half  of  the  total  wind  pressure  concentrated 
at  the  panel  i)oints  of  the  top  chords. 


^ 
'i 


■* 


OKD/XAK )  ■  /A'O.y   I  IK  ///  W.W  '-H  RIDGES. 


23 


ul  IiL'xaL^onal 
taken  from 
opting  those 
a  sliij;ht  ten- 
ensions  may 
:y,  until  the 
h. 

ve  a  uniform 
le  heads  and 
I  wood, 
leam  hangers 
be  provided 

jaws  for  the 
respect,  that, 
will  fail  near 

connect  each 
J  should  be  of 
d,  no  depend- 
I  or  stiffness. 

intermediate 
bsion  induced 
ward  and  lee- 
h  the  bracket 

compression 
concentrated 


Cut  tins;  off  the  I'laiigcs  of  Cliatincls.  — The  llanges  at  the  ends 
of  channel  bars  must  not  be  cut  away,  if  it  be  practicable  to 
a\()i(l  doing  so  :  if  not,  there  must  be  sufficient  re-enforcing 
used  to  make  the  strut  as  strong  as  it  would  have  been  with 
the  flanges  uncut. 

Sizes  of  /■'/ooriiig  and  Joists.  —  Pine  flooring  is  to  be  at  least 
tiirec  (,^)  inches  thick,  and  oak  flooring  at  least  two  and  a  half 
(j.i)  inches  thick.  It  is  to  be  laid  with  close  joints,  anil  well 
spiked  to  each  alternate  joist  with  two  (2)  seven  (7)  inch  cut 
spikes.  Consecutive  boards  should  not  be  spiked  to  the  same 
joists. 

Joists  are  to  be  proportioned  by  the  formula, 


JF  = 


ch 


where  W  is  the  safe  uniformly  distributed  load  in  tons,  b  the 
hreadtli  of  the  joist  in  inches,  d  the  depth  of  same  in  inches, 
/the  length  in  feet,  and  c  —  16  for  jjine  and  1 1.5  for  oak. 

Where  the  greatest  load  is  a  concentrated  one,  it  is  to  be 
considered  as  supported  equally  between  the  joists  directly 
under  the  wheels  and  those  contiguous  to  the  same  ;  i.e.,  the 
wheels  on  one  side  of  a  wagon  are  supposed  to  be  placed 
directly  over  a  joist,  which  joist  is  assumed  to  take  half  their 
load,  the  remaining  half  being  equally  divided  between  the  two 
adjacent  joists.  All  concentrated  loads  must  be  reduced  to 
equivalent  uniformly  distributed  loads  in  respect  to  deflection 
by  multiplying  them  by  one  and  si.\-tenths  (1.6)  before  applying 
the  formula. 

Wooden  Hand  Rails,  etc.  —  Wooden  hand  railing  is  to  be 
made  of  pine,  the  posts  being  4"  X  6"  X  4',  with  two  runs  of 
2"  X  6"  timbers  —  one  on  its  flat,  and  the  other  below  on  edge  to 
support  the  first  for  a  hand  rail  —  and  one  run  of  2"  X  12"  hub 
plank.  The  latter  and  the  lower  run  of  2"  X  6"  timber  are  to 
be  let  into  the  posts  to  their  full  depth,  and  spiked  to  the  same 
with  five  (5)  inch  cut  spikes  ;  and  the  posts  are  to  be  halved 
on  the  outer  joists,  to  which  each  one  is  to  be  bolted  by  two 
(2)  three-quarter  (|)  inch  bolts. 

Guard  rails  are  to  be  of  C"  X  6"  pine,  bolted  to  each  hantl- 


24  ORDINARY  JRU.X  lUCllW AY-BRIDGES. 

rail  post,  and  to  the  floor  once  in,  at  most,  cvc-ry  five  (5)  feet, 
by  three-quarter  (|)  inch  bolts. 

When  there  are  no  wooden  hand-rail  posts,  the  guard  rails 
must  be  bolted  through  joists  placed  symmetrically  below  them, 
care  being  taken  that  there  be  no  bolt  within  two  (2)  feet  of  the 
middle  point  of  any  joist. 

The  joints  in  the  guard  rails  are  to  be  lap  joints,  six  inches 
long,  and  are  to  have  a  bolt  passing  through  the  middle  of  each 
lap. 

About  every  eighth  or  tenth  plank,  there  is  to  be  a  crack  left 
between  flooring  boards  to  let  the  water  run  through  :  this 
crack  should  be  less  than  a  quarter  (|)  of  an  inch  in  width. 

Should  it  be  considered  desirable  to  elevate  the  guard  rails 
in  order  to  let  the  air  and  water  pass  beneath,  it  is  to  be  accom- 
plished by  inserting  hard-wood  shims  —  one  (1)  fool  long  by  two 
(2)  inches  deep,  and  six  (6)  inches  wide  —  beneath  the  guard  rails 
at  each  bolt  hole ;  the  bolt  passing  through  the  middle  of  the 
shim,  and  each  shim  being  fastened  to  the  floor  by  four  (4)  five 
(5)  inch  cut  spikes. 

Ii'ou  Hand  Railing.  — Bridges  with  sidewalks  v.-ill  not  require 
the  wooden  hand  railing  inside  the  trusses,  but  are  to  be  pro- 
vided with  a  neat,  substantial  iron  hand  rail  on  the  exterior  of 
each  sidewalk.  It  is  to  be  rigidly  attached  to  the  floor  beams 
and  exterior  sidewalk  joists. 

Details  not  prcvionsly  Mentioned.  —  Finally,  as  regards  the 
proportioning  of  any  structure,  if  cases  should  occur  which  are 
not  covered  by  the  preceding  specifications,  the  following  rule 
is  in  all  such  cases  to  be  adhered  to  :  "  Details  must  always 
be  proportioned  so  as  to  resist  every  direct  and  indirect  stress 
that  may  ever  come  upon  them  under  any  probable  circum- 
stances, without  subjecting  any  portion  of  their  material  to  a 
stress  greater  than  tlie  legitimate  corresponding  working-stress." 

Cast-iron.  —  No  cast-iron  is  to  be  used  except  for  washers 
for  timber  bolts,  and  for  ornamental  work  and  name  plates. 

Name  Plates. — The  names  of  the  designer  and  the  manu- 
facturer of  the  bridge  must  be  attached  thereto  in  a  prominent 
position  and  in  a  durable  manner. 

Field  Riveting.  —  I-'ield  riveting  must  be  done  with  the  button 


OND/X.INV  /KOX  IIIGHU'AY-IiRinGES. 


!5 


•egards   the 
r  which  arc 


or  washers 


1  the  button 


sett.     The  heads  of  the  rivets  must  be  hemispherical,  and  no 
rou<;ii  edges  must  be  left. 

Paiutiiii^.  —  i\\\  finished  work,  before  leaving  the  shop,  shall 
he  thoroughly  cleaned  from  all  loose  scale  and  rust,  and  covered 
with  one  good  coat  of  pure  boiled  linseed-oil  well  worked  into 
all  joints  and  open  spaces.  In  riveted  work  all  surfaces  coming 
into  contact  shall  be  painted  before  being  riveted  tofether. 

Ik'd  plates,  and  all  parts  of  the  work  which  will  not  be  acces- 
sible for  painting  after  erection,  shall  have  two  coats  of  paint. 

i'ins,  i)orcd  jjin  holes,  and  turned  friction  rollers,  shall  be 
coated  with  white  lead  and  tallow  before  being  shipped  from 
the  shop. 

After  the  structure  is  erected,  the  iron-work  shall  be  cleansed 
from  mud,  grease,  or  any  other  objectionable  material  that  may 
be  found  thereon,  then  thoroughly  and  evenly  painted  with  two 
coats  of  jiaint  mixed  with  pure  linseed-oil,  of  a  color  pleasing  to 
the  eye  ;  the  tension  members  being  generally  of  a  lighter  shade 
than  the  compression  members. 

Wherever  it  be  possible  to  so  design  it,  the  iron-work  must 
be  made  accessible  to  the  paint-brush. 

Tititbcr.—  KW  timber  is  to  be  of  the  best  quality,  free  from 
wind-shakes,  large  knots,  decayed  wood,  sap,  or  any  defect  that 
would  impair  its  strength  or  durability. 

Quality  of  Workmanship.  —  All  workmanship  is  to  be  first- 
class  ;  abutting  joints  are  to  be  truly  planed  and  dressed,  so 
as  to  insure  a  perfect  bearing ;  the  pin  holes  in  chords,  batter 
braces,  and  posts,  are  to  be  bored  as  truly  as  is  specified  for  the 
eye  bars  ;  and  there  are  no  rough  edges  or  corners  to  be  left  on 
the  iron-work. 

15ars  which  are  to  be  placed  side  by  side,  or  in  similar  posi- 
tions in  the  structure,  shall  be  bored  at  the  same  temperature, 
and  of  such  equal  length,  that,  upon  being  piled  on  one  another, 
the  pins  shall  pass  through  the  holes  at  both  ends  without 
driving.  Whenever  necessary  for  the  protection  of  the  thread, 
provision  shall  be  made  for  the  use  of  pilot  nuts  in  erection. 

Quality  ami  Tests  of  Materials.  —  All  wrought-iron  must  be 
tough,  fibrous,  and  uniform  in  character.  It  shall  have  a  limit 
of  elasticity  of  not  less  than  twenty-six  thousand  (26,000) 
pounds  per  square  inch. 


26 


OA'V/X.lA'i'  /A'O.V  HlCllUAY-llRIDGES. 


Il: 


Finished  bars  must  be  thoroughly  welded  during  the  rolling, 
and  free  from  injurious  seams,  blisters,  buckles,  cinder  spots,  and 
imperfect  edges. 

lu)r  all  tension  members  the  muck  bars  shall  be  rolled  into 
flats,  and  again  cut,  piled,  and  rolled  into  finished  sizes. 

They  shall  stand  the  following  tests.  Full-sized  pieces  of  flat, 
round,  or  square  iron,  not  over  four  and  a  half  (4,})  scjuare  inches 
in  sectional  area,  are  to  have  an  ultimate  strength  of  fifty  thou- 
sand (50,000)  pounds  per  scjuarc  inch,  and  are  to  stretch  twehc 
and  a  half  (12.])  per  cent  of  their  whole  length. 

Bars  of  a  larger  sectional  area  than  four  and  a  half  (4^)  square 
inches  arc  to  be  allowed  a  reduction  of  one  thousand  (i,ooo) 
pounds  per  square  inch  for  each  additional  square  inch  of  sec- 
tion, down  to  a  minimum  of  forty-six  thousand  (46,000)  pounds 
per  square  inch. 

Specimens  of  a  uniform  section  of  at  least  one  (i)  square 
inch,  taken  from  bars  of  four  and  a  half  (4])  square  inches  sec- 
tion, and  under,  are  to  have  an  ultimate  tensile  strength  of 
fifty-two  thousand  (52,000)  pounds  per  square  inch,  and  are  to 
stretch  eighteen  (18)  per  cent  in  eight  (<S)  inches. 

Similar  specimens  from  bars  of  a  larger  section  than  four  and 
a  half  (4.^)  square  inches  are  to  be  allowed  a  reduction  of  five 
hundred  (500)  pounds  per  square  inch  for  each  additional  square 
inch  of  section,  down  to  a  minimum  of  fifty  thousand  (50,000) 
pounds  per  square  inch. 

Similar  sections  from  angle  and  other  shaped  iron  are  to  have 
an  ultimate  strength  of  fifty  thousand  (50,000)  pounds  per 
square  inch,  and  are  to  stretch  fifteen  (15)  per  cent  in  eight  (8) 
inches. 

All  iron  for  webs  of  plate  girders  is  to  have  an  ultimate 
strength  of  not  less  than  forty-six  thousand  (46,000)  pounds 
per  square  inch  of  area  of  test-piece,  and  is  to  have  a  minimum 
elongation  of  ten  (10)  per  cent  in  eight  (8)  inches. 

Rivets  are  to  be  of  the  best  quality  of  double  refined  iron. 

The  cast-iron  must  be  of  the  best  quality  of  soft  gray  iron. 

Test  of  Structure.  —  On  the  completion  of  the  entire  struc- 
ture, any  bridge,  after  being  in  constant  use  for  one  day,  may 
be  tested  by  a  load  equal  to  that   for  which   it  was  designed 


O/v'DLV.l/CV  /A\hV  n/GI/WA  V-nN/DGES. 


27 


remaining  upon  it  for  at  least  one  hour,  then  removed,  and 
placed  upon  it  again.  The  first  removal  of  the  loatl  may  show 
a  little  permanent  set ;  but,  when  the  second  load  is  ap|)lied, 
the  total  deflection  must  not  be  any  greater  than  it  was  for  the 
first  loading,  and  upon  its  removal  the  bridge  must  return  to 
the  exact  position  which  it  occupied  after  the  removal  of  the 
first  loading. 


28 


ORD/XA N 1 '  //.'( ^\'   ///( /// U'.n  -/}N/1)(.;ES. 


CHAPTER   III. 

T.IST   OK    MF:M1!KRS. 

In  the  followinj;  list  of  momliors  will  be  found  the  names  of 
all  the  parts,  both  of  wood  and  iron,  in  the  bridj^es  with  wliich 
this  treatise  deals.  Its  use  will  be  explained  in  Chapter  XIV. 
It  is  inserted  here  so  that  those  unacquainted  with  bridf;e 
designing;  may  inform  themselves  as  to  the  names  of  all  the 
parts  of  a  bridge  before  proccedin<;  farther.  This  they  can  do 
by  consultinj;-  the  Cilossary,  and  referring;  to  the  i)lates  there 
indicated.  The  author  would  advise  students,  before  proceeding 
to  Chapter  IV.,  to  study  closely  Plates  I. -IV.,  so  as  to  obtain  a 
general  idea  of  how  bridges  are  constructed. 

LIST  OF  MEMBERS  IN  A  WROUGHT-IRON  HIGHWAY-BRIDGE. 


M.MN    PORTIONS. 

Channel  Bars.  —  Top  chords,  batter  braces,  bottom  chords, 
posts,  upper  lateral  struts,  end  lower  lateral  struts,  upper  portal 
struts,  lower  portal  struts,  hip  verticals  in  pony  trusses. 

Plates.  —  Top  chords,  batter  braces. 

I-Beams.  —  Floor  beams,  intermediate  struts,  end  lower  lateral 
struts,  bottom  chords. 

Bars  and  Rods.  —  Main  diagonals,  counters,  hip  verticals, 
upper  lateral  rods,  lower  lateral  rods,  vibration  rods  at  portals, 
vibration  rods  on  posts,  chord  bars. 

Angle  Iron.  —  Side  bracing,  end  lower  lateral  struts. 

Iron  hand  railing. 

Floor  beams. 

DET.\ILS. 

Stay  Plates.  — Top  chords,  batter  braces,  ends  of  posts,  mid- 


s. 


( >A-J)/X.  IRV  /A'O.V  1  Hi.:  nil  -A  J  -liKt  IHlllS. 


-9 


he  names  of 
s  with  which 
hapter  XIV. 
with  brid<;c 
»s  of  all  the 
they  can  do 
plates  there 
■e  proceeding; 
s  to  obtain  a 


\Y-BRIDGE. 


ttom  chords, 
upper  portal 

isses. 

lower  lateral 

u|)   verticals, 
Is  at  portals, 

uts. 


)f  posts,  mid- 


dle of  i)i)sts,  bottom-chord  channels,  upper  lateral  struts,  end 
lowrr  latt'ral  struts,  up])er  portal  struts,  lowrr  portal  struts. 

Ri-iiifoiriiii^ and Coiuuctiiii^ or  SI'Hcl-  /Wit^s.  —  Hip  inside,  Iiip 
outside,  top-clinrd  intermediate  jiaml  points  inside,  top-chord 
iiilerniediate  panel  points  outside,  holtoni-tliord  struts  at  shoe, 
l)ottom-ch()rd  struts  at  first  panel  points,  shoe  inside,  shoe  out- 
side, lower  enils  of  posts  insiile,  lower  ends  of  jiosts  outside,  mid- 
dle of  posts  inside,  middle  of  i)osts  outside,  lateral  struts  U)  to|) 
ihoids,  up|)er  portal  struts  to  batter  braces,  lower  portal  struts 
to  hatlL'r  braces,  portal  struts  to  brackets  and  name  plates, 
iiitennediate  struts  to  posts,  side  bracinuj  to  floor  beams,  end 
lower  lateral  struts  to  pedestals. 

(\nrr  P/atis.  —  Hip  joints,  joints  at  intermediate  panel  points 
of  to|)  chords. 

I'i/liiii^  Plates.  —  Hips,  intermediate  panel  points  of  top  chord, 
over  end  floor  beams,  between  pedestals  and  lateral  struts. 

ICxtension  plates  at  upper  enils  of  posts,  shoe  plates,  roller 
plates,  bed  plates,  beanvhanger  jilates,  name  plates. 

/,(?(-///i,'-  or  Latticing.  — Top-chord  channels,  batter-brace  chan- 
nels, bottom-chord  channels,  post  channels,  upper  lateral  strut 
channels,  end  lower  lateral  strut  channels,  upper  portal  struts, 
lower  portal  struts,  hip  verticals  in  pony  trusses. 

y'/v/.ovV/i,'-.  —  Hip  verticals  in  pony  trusses,  lower-chord  bars. 

/V//.S-. — Top  chords,  bottom  cliords,  middle  of  posts,  lower 
lateral  rod  connection  to  jaws,  vibration-rotl  connection  to  upper 
portal  and  lateral  struts,  vibration-rod  connection  to  lower  portal 
struts,  between  floor  beams  and  beam-hanger  plates. 

Bolts.  —  Brackets  to  portal  struts  and  lateral  struts,  brackets 
to  batter  braces  and  posts,  name  plates  to  jwrtal  struts,  vibra- 
tion rods  to  lateral  struts,  vibration  rods  to  intermediate  struts, 
bed  plates  to  piers  (anchor  bolts),  shoes  to  bed  plates,  expansion 
pedestal  connection  to  bed  plates,  portal  struts  to  batter  braces, 
iiand-rail  posts  to  joi.sts,  lower  lateral  struts  to  floor  beams, 
lower  lateral  struts  to  jaws,  felly  planks  to  floor  and  hand-rail 
posts. 

Brackets  or  Knee  Braces.  —  Portal  struts  to  batter  braces, 
upper  lateral  struts  to  posts,  intermediate  struts  to  posts. 

Ornamental  work  at  portals,  beam  hangers,  expansion  rollers, 


30 


ORDINARY  IROX  IllGllWlV-BRlDGES. 


roller  frames,  fillers  for  pins,  turn  buckles,  sleeve  nuts,  ronnect- 
in^'-iiiord  heads  for  bt)tl()ni  chord  channels,  jaws  for  lateral  and 

portal  struts. 

Ati}^lc  //vw.  — natter  braces  to  shoe  plates,  sides  of  roller 
plates,  ends  of  roller  plates. 

Picas  of  Chanmb.  —  Hearins  for  bent  eyes  of  upper  lateral 
rods,  bearinj;  for  bent  eyes  of  lower  lateral  rods,  batter-brace 
connectioh    o  shoe  plates. 

Kivif  Heads.  —  Tlate  to  chord  and  batter-brace  channels,  lat- 
ticin-;  or  lacing  to  channels,  latticing;  to  latticing,  the  various 
stay  plates  to  channels,  the  various  connecting  and  re-enforcing 
plates  to  channels,  connecting  plates  to  shoe  plates,  connecthig 
plates  to  intermediate  struts,  connecting  plates  to  side  bracing 
and  floor  beams,  connecting  plates  at  pedestals  to  pedestals  and 
lateral  struts,  cover  plates  to  chords,  extension  plates  to  posts, 
trussing  to  hip  verticals  and  posts,  trussing  to  chord  bars,  orna- 
mental work  to  portals,  brackets  to  posts  and  batter  braces, 
brackets  to  portal,  lateral,  and  intermediate  struts,  components 
of  jaws  to  each  other,  angle  irons  to  shoe  plates,  angle  irons  to 
roller  plates,  the  various  pieces  of  channels  to  the  parts  which 

they  connect. 

5y,//vx  —  Flooring  to  joists,  hand  rails  to  posts,  hub  planks 
to  posts,  felly  planks  to  flooring,  joists  to  lower  lateral  struts, 
jaws  to  lower  lateral  struts. 

Waslicrs.  —  Hand-rail  post  bolts,  bolts  connecting  lateral  struts 
to  floor  beams,  felly-plank  bolts. 

^\^/^/.s-.  —  On  pins,  on  bolts,  on  beam  hangers,  lock  nuts  on 
beam  hangers,  pilot  nuts. 

Details  for  a  Built  Floor  Beam.  —  Web,  upper-flange  angles, 
lower-flange  angles,  top  plate,  bottom  plate,  stiffening  angles, 
filling  plates,  re-enforcing  plates  at   beam-hanger  holes,  rivet 

heads. 

Details  for  a  Trussed  Beam.  —  Rolled  I-beam  for  upper  chord, 
lower-chord  bars,  end  diagonals,  counters,  I-beam  posts,  con- 
necting plates  for  posts  to  beam,  re-enforcing  plates  at  feet  of 
posts,  pin  plates  for  end  diagonal  connection  to  beam,  stiffeners 
at  supports,  pins  and  nuts  on  same,  fillers,  turn  buckles  or 
sleeve  nuts,  rivet  heads. 


lateral  struts 


lock  nuts  on 


0/\/)/.y.lA-r  /I'lKV  Jl/UJ/lfA  V-IiKUHiLS. 


31 


f.iniil'tr.  —  Joists,  flooring,  hand-rail  pieces,   hand-rail  posts, 
lull)  planks,  felly  planks  or  guard  rails,  lower  lateral  struts. 


es  of    roller 


DI/PAILS    roR    A    SPAN    COMI'OSED    OK    PI.ATK    (ilROKKS. 

Webs,  upper-flange  angles,  lower-flange  angles,  top  plates, 
bdttoin  plates,  stiffening  angles,  filling  plates,  angles  for  lateral 
braces,  connecting  plates  for  lateral  braces,  shoe  plates,  bed 
plates,  anchor  bolts  and  nuts,  rivet  heads. 


32 


OKDL\AJ<]-  JNO.X  HluUWA  V-HRlDuES. 


CHAPTER    IV. 


LIVE   AND    DEAD    l,(  )ADS.— WIXD    PUKSSURE. 


As  stated  in  Cliaptor  1 1.,  lii^Ii\vay-liri(ls;os  are  divided  into 
throe  elasses,  A,  B,  and  C,  whieh  arc  res])ectively  for  loeations 
where  the  loads  are  heavy  and  of  frequent  oecurrenee,  loea- 
tions where  the  loads  are  occasionally  heavy,  and  locations 
where  the  loads  are  li_nht. 

After  deeidinj;'  ui^on  the  lenfjth  of  sjian,  width  of  roadway, 
and  class  of  hridi;e  for  any  location,  the  live  load  per  s(|uare 
foot  of  floor  is  to  be  taken  from  the  table  on  p.  5.  The  reason 
why  lont;  sj)ans  maybe  proportioned  for  lii;-hter  loads  than  short 
ones  is  the  very  small  probability  of  a  loni;-  span  e\er  beini;' 
covered  bv  the  maximum  loatl,  while  there  is  a  chance  of  sucii 
ai.  event  takinj;'  place  in  case  of  a  short  span. 

It  can  easily  be  seen,  then,  that,  in  all  bridt^es  of  any  hiirth 
of  span,  each  jianel  should  be  proportioned  to  sustain  the  maxi- 
mum load  ;  for  it  is  possible  to  load  one  panel  heavily  without 
loadin^f  any  of  the  others. 

This  panel  excess  will  affect  only  the  sizes  of  the  joists,  floor 
beams,  beam  hangers,  and  hip  verticals.  Sometimes  the  jxinel 
excess  is  sup})osed  to  exist  when  the  bridt;e  is  partially  or 
wholly  covered  by  the  movinj;'  load,  thus  aflectin,<4'  all  the  main 
membei-s  of  the  trusses  ;  but  this  is  too  nnich  letinement  for 
highwav-bridt;e  desii;-ninL;'. 

The  dead  load  per  lineal  foot  is  to  be  taken  from  one  of 
Tables  1.,  II.,  and  III.,  if  there  be  no  special  loadin<j:  such  as 
that  tlue  to  snow,  if  the  style  of  hantl  railini;-,  i;uard  rail,  etc., 
for  the  bridj^e  to  be  designed,  corresiiimd  with  that  adopted  in 
this  work,  if  the  wiilth  of  roadway  correspond  with  one  of  those 
in  the  table,  and  if  the  length  of  the  siian  be  exactly  divisible 


(>A'/)/x.iA'y  /A'o.v  J //amy A  y-/uu/)g/':s. 


Zl 


divided  into 
'  for  locations 
iirrcnce,  loca- 
and   locations 

1  of  roadway, 
d  per  sc|uare 
The  reason 
ids  than  short 
n  e\er  Ikmiil;' 
lance  of  sucli 

of  any  hiii'ih 
;ain  the  maxi- 
.'avily  without 

le  joists,  floor 
nes  the  panel 
■;  partially  or 
;■  all  the  main 
^'tinenient   for 

from  one  of 
idinii;  such  as 
lard  rail,  etc., 
It  adopted  in 
1  one  of  those 
actly  divisible 


by  Icn.  If  either  or  both  of  the  last  two  conditions  be  not 
fulfdled,  the  dead  load  is  to  be  directly  interpolated  ;  then  if 
there  be  any  difference  in  the  lumber,  or  any  special  loadin<,^. 
the  effect  of  the  chan.i^e  or  changes  is  to  be  calculated  by  the 
method  to  be  explained  presently. 


The  weiurhts  of  iron  and   lumb 


LT  given  in  Tables  I.,  II.,  and 
III.,  are  the  results  of  calculations  for  the  bills  of  materials  of 
sixty  bridges,  so  chosen  in  respect  to  length  of  span,  and  width 

e  weights  vary 
e   most   eco- 


(if  roadway,  as  to  indicate  the  laws  by  which  th 
with  these  dimension.s.     All  the  bridges  are  of  th 


nomic  (le 


\\\ 


th  t 


ie  (hm 


fiv 


e  colunms  un 


pth  and  panel  length,  corresponding  in  these  respects 
ensions  given   in  Table   IV.     The  figures  in  the 

weights 
ems,  and  floor 
Jot,  not  includinj 


der  each  roadway  gi\e  respectively  the 


of  iron  per  lineal  foot  in  the  tru.sses,  lateral  syst 
system  ;  the  weight   of  lumber  per   lineal   fo 


was 


te;  and  the  dead  load  per  lineal  foot,  corrected  for  the  small 


amount  resting  on  the  i)iers. 

To  find  the  dead  load  for  any  span  where  there  is  to 


increased  weight  of  floorinf:,  or 


be 


an 


an  additional  load,  find  th 


value  for  the  weight  of  lumber  (proportioning  the  ioist 


methoi 


n\ 


WCl 


■hs  t 


en  in  Chapter  IX.,  remembering  that 


e  new 
by  the 


pine  lumber 


wo  pounds  and  a  half  per  foot,  board  measure,  and  oak 


lumber  four  pounds  and  a  thirtl),  then  that  of  the  fl 
by  the  formula 


oor  system 


where  F'  is  the  weight  per  foot  of  the  floor  system  required,  F 
that  of  tiie  floor  system  given  in  the  table,  ami  r  (greater  than 
unity)  the  ratio  of  total  loads  on  floor  beams  in  the  two  cases 
considered. 

Next  assume  T\  the  new  value  for  the  weight  T  m  the  truss 
column,  and  find  the  ratio  ;-'  (greater  than  unity)  of  total  loads 
per  foot  on  trusses  in  the  two  cases  ;  then 

If  the  value  of  T'  thus  found  agrees  with  that  assumed,  all  right ; 
'1  not,  It  will  be  necessary  to  try  again  until  it  does  agree. 


34 


ORDINARY  IRON  HIGHWAY-BRIDGES. 


Next  add  together  the  differences  between  T'  and  T,  between 
F'  and  F,  and  between  the  weights  of  lumber  per  lineal  foot. 
To  the  sum  of  these  differences  add  the  weight  of  snow  or 
other  special  loading  per  lineal  foot  of  bridge,  and  the  dead 
load  taken  from  the  table.     The  final  sum  will  be  the  dead  load 

required. 

To  find  the  dead  load  for  a  bridge  with  sidewalks,  look  in 
the  table  of  the  class  to  whicli  the  bridge  belongs,  and  find  the 
weights  for  a  bridge  of  the  same  span  and  roadway  without 
sidewalks,  then  estimate  the  increments  of  these  weight."  as 

follows  :  — 

First,  the  weight  of  lumber  per  lineal  foot  on  the  sidewalks 
is  to  be  calculated  ;  and  from  it  is  to  be  subtracted  twenty-four 
pounds,  which  is  the  weight  per  foot  of  the  wooden  hand  rails, 
hub  planks,  and  hand-rail  posts  (lumber  not  required  when  there 
are  sidewalks).  The  difference  will  be  the  increment  for  the 
"lumber"  column. 

The  increment  for  the  "  lateral  system  "  column  will  be  zero  : 
that  for  the  "  floor  system  "  column  can  be  found  approximately 
by  the  formula 


/  = 


2bF 


where  /  is  the  increment  required,  F  the  weight  per  foot  of 
floor  system  taken  from  the  table,  b  the  sum  of  the  widths 
of  the  sidewalks,  and  /;  the  clear  width  of  main  roadway. 

The  increment  of  the  "truss"  column  is  found  by  assuming 
the  dead  load  required,  and  calling  it  W'l,. 
Let 

IVa  =  tlie  dead  load  given  in  the  table, 

p^  _  the  live  load  per  lineal  foot  on  the  main  roadway, 

Pi,  =  that  on  the  sidewalks ; 


then 


Let 


Pa  +  //;, 

T„  =  the  truss  weii^lit  from  the  table, 
7),  —  the  new  iriiss  weit;ht ; 


ORDINARY  IRON  HIGH  WAY-BRIDGES. 


35 


then 


1  roadway, 


s. 


Ty 


^(- 


^{Pa\-Pl,-^Wt)\ 


and  the  increment  will  be  T/,  —  T„- 

Next  add  /F„,  the  three  increments  found,  and  the  weight 
per  lineal  foot  of  the  iron  hand  rails  :  the  sum  will  be  the  dead 
load  required.  If  it  agrees  with  the  assumed  load  IVt,  all  right ; 
if  not,  another  trial  for  the  new  truss  weight  is  to  be  made. 

There  is  one  case  in  which  this  method  would  give  too  trreat 
a  result :  it  is  that  of  a  pony  truss  with  side  braces,  of  which 
the  only  representative  in  the  tables  is  the  sixty-foot  span.  To 
apply  the  method  to  this  case,  it  will  be  sufificiently  exact  to 
use  the  weight  of  floor  system  of  the  fifty-foot  span,  because  the 
floor  beams  of  the  sixty-foot  span  project  beyond  the  trusses. 
This  change  being  made,  the  method  can  be  otherwise  followed 
exactly. 

The  full  double  horizontal  lines  in  Tables  I.,  II.,  and  III., 
divide  the  single  from  the  double  intersection  trusses. 

All  the  bridges  in  Table  III.  lying  to  the  left  of  the  double 
vertical  line  which  separates  the  twenty-two-foot  and  twenty- 
fnur-foot  roadways,  have  stiffened  end  panels.  The  correspond- 
ing lines  of  division  in  Tables  I.  and  II.  separate  the  twenty-foot 
and  twent}-two-foot  roadways. 

The  weights  of  iron  in  Tables  I.,  II.,  and  III.,  do  not  include 
tlw  'u'cig/it  of  the  spikes. 

It  is  seldom  necessary  to  make  an  allowance  for  snow  load  in 
bridges  of  Class  C,  but  it  may  be  advisable  to  do  so  in  bridges 
of  Classes  A  and  B;  for,  after  a  heavy  snow-storm,  the  travel 
nn  country  roads  would  be  light,  which  would  not  necessarily 
the  case  in  a  city  or  its  suburbs.  The  proper  allowance 
snow  load  should  be  from  ten  (lo)  to  thirty  (30)  pounds 
er  square  foot  of  floor ;  according  to  climate,  locality,  proba- 
bility of  greatest  live  load  occurring  simultaneously  with  the 
.siKJW  load,  etc. 

As  stated  in  Chapter  II.,  the  wind  pressure  assumed  is  forty 
(40)  pounds  per  square  foot  for  spans  of  one  hundred  (100)  feet 
and  under,  thirty-five  (35)  pounds  for  spans  between  one  hun- 
dred (100)  and  one  hundred  and  fifty  (150)  feet,  including  the 


36 


ORDINARY  IRON  HIGHWAY-BRIDGES. 


latter,  and  thirty  (30)  pounds  for  all  greater  spans.  It  is  true 
that  actual  wind  pressures  do  occasionally  exceed  these  amounts  ; 
but  in  view  of  the  fact  that  the  chance  of  any  one  bridge  ever 
being  subjected  to  such  pressure  throughout  its  whole  length 
is  extremely  small,  and  that  it  could  receive  once  in  a  while 
a  far  greater  pressure  without  suffering  material  injury  if  tlic 
bridge'  be  properly  designed,  it  seems  legitimate  to  adopt  the 
pressures  assumed. 

Moreover,  when  a  highway-bridge  is  blown  down,  the  actual 
loss  is  seldom  much  greater  than  the  cost  of  a  new  bridge. 
Travellers  can  cross  the  stream  at  the  nearest  bridge  above  or 
below,  until  the  structure  be  replaced.  And  the  fall  of  the  bridge 
need  involve  no  loss  of  life  :  for,  in  the  f^rst  place,  no  human 
being  would  be  likely  to  be  upon  it  in  such  a  storm  ;  and,  in 
the  second,  if  there  were,  he  could  not  escape  being  dashed  to 
pieces  or  blown  off,  even  if  the  bridge  were  sufificiently  rigid 
to  withstand  the  pressure. 

With  railroad-bridges,  of  course,  it  is  a  very  different  matter. 
The  delay  caused  by  the  loss  of  such  a  bridge  may  be  much 
more  expensive  than  the  replacing  of  the  structure.  Besides, 
railroad-bridges  are  subjected  to  the  greatest  wind  pressure 
when  covered  by  a  train  ;  so  that  the  fall  usually  involves  the 
loss  of  human  life. 

If  the  lateral  systems  of  highway-bridges  were  ^o  be  made  as 
strong  as  those  of  railroad-bridges,  unstiffened  eye-bars  could 
be  very  seldom  employed  for  the  bottom  chords ;  because  the 
compression  there  due  to  the  wind  pressure  would  be  far  in 
excess  of  the  tension  due  to  dead  load  (%ndc  Appendix  I.). 

Even  with  the  pressures  assumed,  it  is  necessary  to  rely  upon 
the  stiffness  of  the  joists  to  prevent  buckling  the  bottom  chords 
of  at  least  two-thirds  of  the  iron  and  combination  highway- 
bridges  in  the  United  States. 

It  is  not  necessary  to  add  any  area  to  the  section  of  the  bot- 
tom chords  to  resist  the  tension  due  to  wind  pressure,  unless 
this  tension  exceeds  that  due  to  the  live  load  multiplied  by 
the  ratio  of  the  intensity  f)f  working  tensile  stress  in  lateral 
systems  to  that  of  working  tensile  stress  in  chords.  Should  it 
so  exceed,  the  chords  should  he  proportioned  to  resist  the  wind 


ORDLXARV  IRON  HIGHWAY-BRIDGES. 


37 


stress  plus  the  dead-load  stress  multiplied  by  the  aforesaid 
ratio,  using  an  intensity  of  seven  and  a  half  (/.])  tons,  or,  in 
case  of  stiffened  eye-bars,  six  and  a  half  (6^)  tons.  This  ex- 
cess should  be  looked  for  in  narrow  bridges  in  unusually 
exposed  situations,  in  the  design  for  which  the  wind  pressure 
has  been  increased  ten  (lo)  pounds  per  square  foot. 

I-\)r  this  same  reason,  of  there  being  no  probability  of  a  live 
l(md  remaining  upon  a  highway-bridge  during  a  heavy  storm, 
the  effect  of  the  wind  upon  posts  and  batter  braces  may  be 
neglected,  unless  the  stresses  produced  thereby  exceed  those 
due  to  the  live  load  multiplied  by  the  ratio  before  mentioned  ; 
in  which  case  the  wind  stresses  should  be  multiplied  by  the 
reciprocal  of  this  ratio,  and  to  the  product  should  be  added 
the  dead-load  stresses,  in  order  to  find  the  greatest  stresses  for 
which  to  ])roportion  these  members.  As  before,  this  excess  is 
to  be  looked  for  when  the  assumed  wind  pressure  has  been 
increased  by  ten  (lo)  pounds  per  square  foot:  it  will  probably 
be  only  the  lighter  posts  that  will  be  so  affected. 

l^ut  the  bending  effect  of  the  wind  pressure  upon  portal  and 
latL'ral  struts,  when  no  vertical  sway  bracing  except  brackets  is 
used,  should  always  be  provided  for. 

The  author  believes,  that,  instead  of  designing  highway- 
bridges  in  ordinarily  exposed  situations  to  resist  the  greatest 
recorded  wind  pressure  in  the  district,  it  is  better  to  run  a 
little  risk  of  losing  a  structure  than  to  make  all  the  britlges 
so  much  more  expensive.  Nevertheless,  he  wishes  it  to  be 
distinctly  understood,  that,  in  advocating  the  adoption  of  com- 
paratively low  wind  pressures,  he  does  not  countenance  the 
buikling  of  such  miserable  apologies  for  lateral  systems  as  one 
rinds  in  the  majority  of  highway-bridges. 


38 


ORDINARY  IROX  HIC-lIW'AV-liRIDGKS. 


CHAPTER  V. 

STRKSSKS   IN   TRUSSES. 

The  length  of  span  having  hecn  decided  by  considerations  of 
both  necessity  and  economy  {vide  Chapter  XV.),  and  the  width 
of  roadway  by  the  requirements  of  travel,  there  remain  to  be 
determined,  before  making  out  the  diagram  of  stresses,  only 
the  style  of  intersection,  panel  length,  and  depth  of  trusses. 
These  matters  are  fully  treated  in  Cluipter  XV.  Meanwhile, 
the  style  of  intersection  may  be  settled  by  remembering  that  the 
single  is  more  expensive  than  the  double,  and  that  the  inferior 
limits  of  the  latter  for  the  different  classes  of  bridges  and  differ- 
ent clear  roadways  are  given  in  the  table  on  p.  8.  The  most 
economic  panel  lengths  and  depths  of  truss  for  locations  wliere 
long  timber  is  expensive,  and,  in  fact,  for  nearly  all  locations, 
are  to  be  taken  from  Table  IV.  For  locations  where  long  tim- 
ber is  very  cheap,  there  can  be  made  a  little  saving  in  the 
iron-work  by  using  Table  V.  instead  of  Table  IV. 

As  is  customary  in  figuring  stresses,  uniformly  distributed 
loads  are  to  be  considered  as  concentrated  at  the  panel  points; 
and  the  half-panel  load  at  each  end  of  the  truss  is  not  supposed 
to  produce  any  stress  in  any  member  of  the  truss. 

The  first  step  in  making  a  diagram  of  stresses  is  to  fill  out 
one  of  the  following  tables  of  data  :  — 


Single  Intersection. 
11  — 

d  = 
diag.  = 
sec  Q  = 


iLMM.E   ISTEUSECTION. 

Doi'Fii.E  Intersecticin, 

;n  Number  of  Panels. 

odd  Number  of  I'.uicls. 

n  — 

n  = 

/  = 

/  = 

d=. 

d  = 

short  diag.  = 

short  diag.  = 

long  diag.  = 

long  diag.  = 

OKJ)/XAKV  /NOX  lllClllVAY-nRIDGES. 


39 


Doi'dLlv    iNTKHMiCTlON. 

DoimtR 

iNTF.RSKCTinN 

SlMiLE    iNTEK-iKCTlON. 

Even  Niinitjcr  of  i'aiicls. 

Odd  Number  of  I'anek 

tan  B  = 

sec  a  = 

sec  a  =  ; 

w  =■ 

tan  u  = 

tan  a  = 

IV,  = 

sec  ft  = 

sec  ft  = 

IV"  = 

70  = 

TV  = 

IV'  = 

^F,= 

PV,= 

I 

JF"  = 

IV"  = 

n 

IV'  = 

IV  = 

-  w  sec  0  = 
w 

I 

1 

~  7V  = 

n 

n\  sec  0  = 
U/;sec6  = 

I 

-  70  sec  «  = 

n     ' 

'/r"tane  = 
^  /F"  tan  6  = 

?Fj  sec  «  = 
I  U\  sec  «  = 

I 

-  IV  sec  «  = 
11 

-  7S.I  sec  i8  = 

Uv, 

sec«  = 

IV,  sec  j8  = 
\  n\  sec  /3  = 

-  7v  sec  fl  = 

]V"  tan  <«  = 
^ff'tan«  = 

n     ' 

sec  /3  = 

-■  W"  tan  «  = 

is  to  fill  out 


where  ;/  is  the  number  of  panels  in  the  span,  /  the  length  of 
each  panel,  d  the  depth  from  centre  to  centre  of  chords,  b  the 
inclination  of  the  diagonal  ties  in  the  single-interspction  truss 
to  the  vertical,  a'  the  live  panel  load  in  tons  on  one  truss  (i.e., 
one-half  the  ]:)roduct  of  the  live  load  per  foot  by  the  panel 
length,  or  one-half  the  product  of  the  clear  roadway  by  the 
l);incl  length  by  the  live  load  per  square  foot  in  pounds,  all 
divided  by  two  thousand),  W,  the  panel  dead  load  on  one  truss, 
W"  —  III  +  //'j,  IV"  the  portion  of  H\  concentrated  at  the  upper 
panel  point,  «  the  inclination  of  the  short  diagonal  ties  in  double- 
intersection  trusses  to  the  vertical,  and  ft  the  inclination  of  the 
long  diagonal  ties  in  same  to  the  vertical.  The  value  of  If"  is 
usually  between  one-foiuth  and  one-third  of  /f'j:  by  taking  it 
always  eqtial  to  one-third  of  Jl\  a  small  error  on  the  side  of 
safety  will  be  made  in  designing  short  spans. 

Having  filled  out  the  table  of  data,  the  next  step  is  to  draw  a 


40 


ORDINARY  IRON  H/GHWAY-nR/DGES. 


skeleton  diagram  large  enough  to  contain  all  the  stresses  and 
sections.  It  is  not  necessary  that  the  diagram  be  drawn  to 
scale  ;  but  the  ratio  of  panel  length  to  depth  of  truss  on  the 
diagram,  for  the  sake  of  appearance,  should  not  vary  too  greatly 
from  the  ratio  of  the  actual  values  of  these  dimensions.  A 
panel  length  of  an  inch  and  a  half,  and  a  depth  of  two  inches 
and  a  half,  are  about  as  small  dimensions  as  will  be  found  con- 
venient. 

At  each  lower  panel  point  write  lightly  in  pencil,  so  th^t  it 
can  be  afterwards  erased,  the  number  of  the  panel  point,  begin- 
ning with  zero  at  the  right-hand  end  of  the  span. 

It  is  well  known,  and  will  be  accepted  here  without  proof, 
that  the  greatest  stresses  in  the  chords  and  batter  braces  occur 
when  the  bridge  is  entirely  covered  by  the  moving  load  ;  that 
the  greatest  stress  in  any  diagonal  exists  when  the  live  load 
extends  to  its  foot  from  that  end  of  the  bridge  towards  which 
the  diagonal  points  in  a  dimiiu'a ni  (Xnccixon  ;  that  the  greatest 
stress  in  any  post  occurs  when  the  main  diagonal  (or,  if  there 
be  none,  when  the  heaviest  counter)  attached  to  its  up[)er  end 
receives  its  greatest  stress  ;  and  that  the  two  diagonals  of  a 
panel  cannot  at  the  same  time  be  subjected  to  the  same  kind 
of  stress,  excepting,  of  course,  the  initial  tension. 

It  is  apparent  that  when  the  greatest  stresses  in  all  the 
diagonals  sloping  upward  in  one  direction,  and  in  all  the  posts 
and  chord  panels  on  one  side  of  the  central  plane,  are  found,  the 
greatest  stresses  in  the  diagonals  shjping  in  the  opposite  direc- 
tion, and  in  the  |)osts  and  chord  panels  on  the  other  side  of  the 
central  plane,  can  be  immediately  written.  This  fact  is  so  well 
known,  that,  in  making  a  diagram  of  stresses,  it  is  usual  to  write 
the  stresses  on  only  one-half  of  the  members  of  the  truss. 

First  let  us  take  a  single-intersection  through-bridge. 

The  greatest  stress  in  any  diagonal  sloping  upward  from  right 
to  left  can  be  found  by  the  formula 


-(//  +  I )     sue  &  +  {  // 

2  /I  \  2 


')'K 


sec  9, 


where  ;/  is  the  number  of  the  j^anel  point  at  the  foot  of  the 
diagonal.     This  formula  is  ai)plicable  to  counters  as  well  as  to 


ORDINARY  IRON  HIGHWAY-URIDCEs. 


41 


main  {liayonals.      If  the  stress  should  come  out    negative,  it 
shows  tiuit  no  counter  is  needed  in  the  panel  considered.     It  is 
also  applicable  to  the  batter  brace  by  putting  (//  —  i)  for  ;/. 
The  stress  in  any  post  can  be  found  by  the  formula 

u  liere  ;/  (not  less  than  "^  is  the  number  at  the  foot  of  the  post. 

The  stress  in  any  panel  of  the  top  chord  is  given  by  the 
formula 


c  z=.  "'(^  ~  ^0 


W"  tan  6, 


wliere  ;/  (not  greater  than  -^  is  the  number  at  the  end  of  the 
panel  nearest  to  the  centre  of  the  bridge. 

The  stress  in  any  panel  of  the  bottom  chord,  except  the  one 
at  the  end  of  the  span,  is  given  by  the  formula 

r=l^jH^Zl^_L),r'tan^. 

;/'  having  the  same  value  as  in  the  last  formula.     For  the  end 
panel,  the  stress  is  the  same  as  for  the  second  panel. 

As  the  values  of  '^,  ^  sec  ^,  and  //;  sec  ^,  are  given  in  the 

table  of  data,  the  substitution  in  these  formulas  is  a  very  simple 

matter.  '         ' 

The  stress  in  the  hip  vertical  is  tc  +  .1  (weight  of  floor  beam 
plus  a  panel  weight  of  lumber),  neglecting  the  weight  of  the 
Dcam  hangers,  end  lower  chord  bars,  etc.,  which  is  not  worth 
considermg.  It  is  not  necessary  to  calculate  this  stress ;  for 
the  section  required,  or  the  size  of  the  square  bars,  if  that 
shape  be  employed,  can  be  taken  immediately  from  one  of 
Tables  VI.,  VII.,  or  VIII. 

Some  engineers  may  object  to  using  formulas  for  figuring 
stresses :  if  so,  the  following  method  will  give  the  same  results 
lor  single-intersection  bridges. 


42 


OA'/)/.\:iA'i-  fh'(h\  //A/////'./ J'-/.'A'//>(;a\v. 


I'ass  ;i  vcMtical  plane  through  the  middle  point  of  the  bottom 
ehoni  •  all  ihe  dead  loads  to  the  ri-ht  of  this  plane  may  be 
c.nsidered  to  k<>  to  the  li-ht-haml  pier,  and  all  to  the  left  of 
the  plane  to  the  leftdianii  pier.  Shonld  there  be  a  post  at  the 
middle  of  the  brid-e.  the  wei-ht  at  the  foot  is  to  be  e.msidere.l 
as  halved,  one-half  goin-  to  each  pier.  Then  the  stress  m  any 
main  diagonal  of  the  left-hand  half  of  the  bridge  is  to  be  f.mnd 
by  eommencin-  at  the  ri-hthand  end,  and  a.ldin-  the  nimd.ers 
at  the  panel  points  until  the  foot  of  the  diagonal  eonsidered  is 

reached,  multiplying  the  sum  by  Sc  sec  ^,  and  to  the  product 
adding  the  number  of  panel  dead  loads  between  the  central 
plane  and  the  panel  point  at  the  foot  of  the  diagonal  considered 
(including  the  one  at  this  point)  multiplied  by  \\\  sec  b. 

Vox  instance,  in  a  ten-panel   bridge,  the  stress  in  the  end 
main  diagonal,  the  number  at  its  foot  being  eight,  will  be 


lO 


(I  +  2  +  3  +  etc.  . 

The  stress  in  a  counter  on  the  right-hand  half  of  the  bridge 
will  be  found  bv  adding  the  numbers  at  the  panel  points 
until  the  foot  of 'the  counter  considered  is  reached,  multiply 

ing  the  sum  by  -  «- sec /^  and  from  the  product  subtracting  the 

dead-load  stress  of  the  main  diagonal  which  crosses  the  coun 
icr      Thus,  in  the  ten-panel  bridge,  the  stress  in  the  second 
counter  from  the  centre  in  the  right-hand  half  of  the  span,  or 
the  one  at  the  foot  of  the  third  panel  point,  is 

The  greatest  stress  in  any  post  is  found  by  adding  W  to  the 
vertical  component  of  the  greatest  stress  in  the  main  diagonal 
attached  to  its  upper  end  ;  thus,  in  the  same  bridge,  the  stress 
in  the  first  post  from  the  left-hand  end,  or  the  one  at  the  eighth 
panel  point,  is 

(x  +  .  +  3-fctc....  +  7)"+(Jf  +  O^J^+^^'- 


()A'/)/A:iA'y  /NOX  niCIIW.lY-lil^lDCES. 


43 


For  the  case  of  a  middle  post,  the  stress  in  one  of  the  coim- 
tiTs  at  the  upper  ^wA  must  be  substituled  for  that  of  tlic  .uaiii 
(lia-onal ;  thus,  in  the  same  bridge,  the  stress  in  tiie  middle 
post  is 

(I  +  2  +  3  +  4),^  -\W,  +  W'. 


btractiiii;  tlie 


The  stresses  ni  the  chords  are  to  be  found  by  the  follow-in- 
nu'thod  :  — 

I'ass  a  plane  throu{,^h  the  foot  of  the  post  at  or  nearest  to  the 
mi. Idle  of  the  truss,  and  take  the  centre  of  moments  at  this 
loot.  I-rom  the  moment  of  the  re-action  at  the  nearest  end  of 
the  l.ridj^a"  subtract  the  sum  of  the  moments  of  the  pane  1  loads 
(//'")  lyinj;  between  the  centre  of  u  mci.ts  and  this  end,  and 
divide  the  dilTerence  by  the  depth  of  the  truss.  The  result  will 
be  the  stress  in  the  panel  of  the  top  chord  nearest  the  centre 
of  the  brid^^e  :  it  will  be  some  multiple  of  //'"  tan  e. 

The  stress  in  tiie  panel  of  the  bottom  chord  immeuiately 
below  will  be  equal  to  the  one  found,  less  the  horizontal  com- 
|)oncnt  of  tile  luaiit  diagonal  of  the  panel,  when  the  brid<;e  is 
covered  by  the  moving  load.  This  horizontal  component"  will 
be  zero  for  a  truss  with  an  odd  number  of  panels,  anti  .i  //'"  tan  0 
lor  a  truss  with  an  even  number  of  panels. 

The  stress  in  the  ne.xt  panel  of  the  bottom  chord  towards  the 
nearest  end  of  the  bridj^e  Is  found  by  subtracting  from  the  one 
already  determined  tlie  horizontal  component  of  the  stress  in 
the  main  diagonal  at  the  panel  point  between  the  two  panels 
considered  ;  the  bridge,  as  before,  being  fully  loaded.  This  com- 
ponent is  a  multiple  of  W"  tan  6.  In  this  way  can  be  found  all 
the  stresses  in  the  panels  of  the  bottom  chord,  the  correctness 
of  the  work  being  checked  by  seeing  if  the  stress  in  the  end 
panel  be  equal  to  the  re-action  multiplied  by  tan  (i.  If  so, 
the  remaining  upiier-chord  stresses  mav  be  at  once  written  by 
mspection;  for  the  stress  in  the  ;/th  panel  of  the  top  chord, 
counting  from  the  nearest  jjier  or  abutment,  and  supplying 
the  missmg  panel  at  the  end,  is  numerically  equal  to  that  in  the 
{it-\-  i)th  panel  of  the  bottom  chord. 

It  seems  almost  unnecessary  to  state,  that  the  stresses  in  the 


44 


oNn/XAKV  //COX  ///<;// ivA y-/i/c//Hi/-:s. 


top  chords,  hatter  hraccs,  and  posts,  arc  compressive,  and  those 
in  liottom  chords,  main  diagonals,  counters,  and  hip  verticals 

tensile. 

Next  let  us  consider  the  double-intersection  truss. 

The  formulas  for  this  case  are  so  complicated  that  it  is  better 
not  to  employ  them.  The  simplest  method  is  to  draw  a  skele- 
ton diagram,  and  number  the  panel  points,  as  in  the  single-inter- 
section truss.  The  double-intersection  truss  really  consists  of 
two  trusses,  as  may  be  seen  in  the  accompanying  diagram. 


D  II  i:t  11!  11  Id   1)    a  j  ;■    »    :<   i    :i   j    i   u 

AhNlxM/IA- 


fig.  3 


IBM       n      10      n     i       i       i      a 


Such  a  division  is  necessary  in  order  to  calculate  the  chord 
stresses  when  the  truss  contains  an  odd  number  of  panels. 
This  is  accomplished  by  finding,  by  the  method  of  moments 
already  explained,  the  chord  stresses  in  each  of  the  trusses 
shown  in  Figs.  2  and  3,  and  then  combining  them.  Thus  the 
stress  in  panel  9-10  of  the  lower  chord  in  Fig.i  is  equal  to 
that  in  panel  9-1 1  of  Fig.  2,  plus  that  of  panel  8-10  of  Fig.  3. 

The  live-load  stress  in  any  diagonal  sloping  upward  from 
right  to  left  is  found  by  noting  whether  the  number  at  its  foot 
be"  odd  or  even,  then  taking  the  sum  of  the  odd  or  even 
numbers,  from  one  or  two  up  to  the  number  at  the  foot  of  the 

to  IV 

diagonal,  and   multiplying  the  sum  by  -  sec  a,  or  -  sec  [i,  as 

the  case  may  be. 

The  stress  due  to  the  dead  load  is  found  by  taking  the  sum 
of  the  same  numbers,  and  from  it  subtracting  the  sum  of  the 
odd  or  even  numbers  from  one  or  two  up  to  n  —  (//'  +  2),  where 
;/  is  the  number  of  panels  in  the  span,  and  //  is  the  number  at 
the  foot  of  the  diagonal  considered. 


Whether  the  odd  or  even 


OA'/>/.\:iA'y  /A'6».v  ///(,// n: I  y-/,'/://h;/:s. 


45 


iiiimhns  should  he  taki-n  can  he  ascertained  hy  followinf?  out 
towards  the  left  the  system  to  which  the  dia^a)nal  helon;;s  :  if 
the  system  contain  the  short  (lia;j;onal  at  tli.it  end,  then  th.- 
even  nimihers  arc  to  he  taken,  otherwise  the  odd  ones. 

The  difference  thus  found,  multiplied  hy  "  '  '*'''-'"  or  ^^'''■' /^, 

'/  // 

as  the  case  may  he,  will  f,Mve  the  dead-load  stress  in  the  dia;;onal. 
Thus,  in  the  diagram,  the  dead-load  stress  in  the  main  diago- 
nal at  the  panel  point  lo  is 


[(2 +  4  4- etc.  +  io)-(i  +3)]-- 


/F,  sec  /3 


As  in  the  case  of  the  sinp;le  intersection,  the  stress  in  a  main 
(liaj;-onal  is  equal  to  the  simi  of  the  live  and  dead  load  stresses  ; 
that  in  a  counter,  to  the  difference  hetvveen  its  live-load  stress 
and  the  dead  load  stress  of  the  main  diaj,fonal  crossin^^  it  at  the 
middle  of  its  len-^th  ;  that  in  a  post,  hy  the  sum  of  //"  and  the 
vertical  component  of  the  Kix-atest  stress  in  the  main  dia-onal 
(or,  if  there  he  none,  that  in  the  principal  counter)  attached  to 
its  upper  end.  As  the  hatter  hraces  helong  to  hoth  systems  of 
triangulation,  their  stresses  are  the  sum  of  the  stresses  found 
hy  each  system,  or  hy  the  formula 

C=[r  +  2  +  3  -f-  etc +  (n  -  ,)]l^:±i51i££i.\ 


If  the  numher  of  panels  he  even,  the  calculation  for  the  dead- 
load  stresses  may  he  much  simpliiietl  hy  coinitin-;  the  numher 
nf  panel  jjoints  on  the  system  considered  lyin^  hetween  the 
central  plane  and  the  panel  point  at  the  foot  of  the  diagonal, 
inchuling  the  latter,  rememherin-,-  th.at  the  load  at  the  middle 
panel  is  halved,  and  multiplying  the  result  hv  Jl\  hcc  a,  or 
/r,  sec/i. 

The  finding  of  the  chord  stresses  is  .also  simplified  when 
there  is  an  even  numher  of  ixmels  ;  for  they  can  then  he  calcu- 
lated hy  the  method  explained  for  the  single-intersection  truss. 

In  every  douhle-intersection  truss,  there  is  neces.sarily  a  little 
amhiguity ;  for  it  is  possihle  that  the  whole  of  the  load  con- 


■}   1* 


46 


ORDLXARV  IROX  IIIGIIWAY-BRIDGES. 


centrated  at  the  first  panel  point  docs  not  travel  by  the  sys- 
tem of  odd  numbers  ;  but  this  ambiguity  is  a  matter  of  small 

moment. 

The  only  difference  between  the  stresses  in  a  deck  bridge 
and  those  in  a  corresponding  through  bridge  will  be  in  the 
posts,  the  stresses  for  which  are  to  be  found  by  letting  the  live 
load  extend  from  the  farthest  end  of  the  bridge  to  the  top  of 
the  post  ;  so  that  the  post  will  no  longer  take  its  greatest  stress 
with  the  main  diagonal  attached  to  its  top,  but  with  the  one 
attached  to  its  foot. 

The    formula   for  post   stresses    in   single-intersection    deck 

bridges  is,  therefore. 


C  = 


t>'{jl'  -    I)+   2 


'i{^\  +  [,,'-.'i±iyv,+w'.* 


To  find  the  stress  in  a  post  of  a  double-intersection  deck 
bridge,  add  ic,  U",  and  the  vertical  component  of  the  greatest 
stress  in  the  principal  diagonal  attached  to  its  upper  end.* 

In  designing  bridges  where  there  is  an  assumed  snow  load,  tlie 
counter  stresses,  and  the  post  stresses  produced  by  the  counters, 
should  be  figured  without  the  snow  load  ;  because,  the  greater 
the  dead  load,  the  less  the  counter  stresses, 

In  Carnegie's  "Pocket-Companion,"  pp.  141-143.  ^'ViH  be  found 
tabulated  the  numerical  co-efificients  for  the  stresses  in  single- 
intersection  trusses  having  from  three  to  twelve  panels,  and  in 
double-intersection  trusses  having  from  eleven  to  twenty  panels. 
The  panel  dead  loads  are  supposed  to  be  concentrated^on  the 

"  *  This  method  of  finding  post  stresses  is  not  exact,  but  gives  an  error  on  the  side  of 
safety,  varying  from  "-  at  the  centre  to  zero  at  the  ends  of  tlie  span :  it  assumes  the  total 
panel  load  «■  to  pass  down  the  i^ost  before  being  divided  into  the  portions  which  i>ass  to 
nglit  and  left,  when  in  fact  the  portion  going  to  the  farther  end  passes  down  the  main  diago- 
nals  as  compression.  Tlie  formula  was  uriginally  obtained  under  tlie  false  assumption  ;  but 
it  has  been  retained  for  the  following  reasons  :  — 

ist,   There  is  a  certain  amourt  of  shock  accomjianying  the  application  of  the  panel  live 

load  on  the  post ; 
2d,   The  load  w  comin^^  from  the  floor  beam  is  applied  to  one  side  of  the  axis  of  the 

post,  and  consequently  tends  to  produce  a  slight  bending  thereon ; 
3d,   The  distribution  of  the  excess  of  stress  is  favorable,  being  greatest  for  the  light  jxjsts 
near  the  middle  of  the  span,  and  smallest  for  the  heavy  ones  near  the  ends. 


ORDIXA  R  Y  IRON  HIGH  WA  J  -BRIDGES. 


section    deck 


47 


bottom  chords  in  through  bridges,  which  will  cause  an  error  on 
the  side  of  danger  in  the  post  stresses  :  this  fact  is  pointed  out 
on  p.  141.  A  slight  difference  will  be  found  between  the  co- 
efficients there  given  for  the  diagonal  and  chord  stresses  of 
double-intersection  trusses  having  an  odd  number  of  panels, 
.uul  those  obtained  by  following  the  method  indicated  in  this 
chapter.  The  latter  will  give  stresses  slightly  in  excess  of 
those  in  the  "Pocket-Companion;"  but  the  difference  is  so 
small,  that  it  is  scarcely  worth  mentioning.  Had  the  engineer 
who  ijrepared  the  tables  been  a  believer  in  the  use  of  long 
panels,  he  would  have  commenced  his  douWe-intersection  trusses 
with  seven  panels  instead  of  eleven. 

Tables   XLI.   and   XLII.   give   the   stresses  for  all  bridges 
treated  in  this  work. 


rsection    dec) 


ion  of  tlie  panel  live 


Ic  of  the  axis  of  tlie 


48 


ORDLXAKY  JRO.X  HlGlilVA  V-BRWGES. 


CHAPTER   VI. 


STRESSES   IN   LATERAL  SVSTEALS   AND   SWAY   BRACING. 

The  wind  loads  concentrated  at  the  panel  points  are  deter- 
mined by  imagininjj;  a  horizontal  plane  passing  through  the 
middle  of  the  truss,  and  supposing  that  the  pressure  on  all 
the  exposed  surface  of  the  bridge  above  this  plane  is  concen- 
trated at  the  upper- panel  points,  and  all  below  this  plane  at  the 
lower-panel  points.  This  may  be  a  correct  assumption,  or 
may  not ;  but  it  is  as  likely  to  be  correct  as  any  other. 

Where  vertical  sway  bracing  is  used,  the  di\'ision  of  wind 
pressure  becomes  still  more  ambiguous ;  but,  as  before,  the 
same  assumption  is  as  likely  to  be  correct  as  any  other. 

In  calculating  the  area  opposed  to  the  wind,  the  area  of  the 
vertical  projectit)n  of  one  truss,  hand  railing,  including  hub 
plank,  guard  rail,  and  the  rectangles  described  about  the 
windward  ends  of  the  floor  beams,  is  to  be  doubled,  and  to  this 
is  to  be  added  the  area  of  the  vertical  projection  of  the  floor 
and  joists. 

As  the  windward  hand  rail  would  probably  fail  under  high 
pressure,  the  total  area  thus  found  is  somewhat  in  excess  ;  but 
such  a  failure  should  not  be  depended  upon  when  the  wind  is 
considered  to  strike  the  bridge  suddenly.  For  spans  of  and 
under  two  hundred,  or  sometimes  even  two  hundred  and  thirty 
feet,  the  sizes  of  the  upper  lateral  rods  are  not  to  be  determined 
by  the  effect  of  the  wind  pressure,  as  this  method  would  make 
them  smaller  than  experience  would  indicate  to  be  necessary 
for  rigidity.     The  sizes  to  be  used  can  be  found  in  Table  XXV. 

The  wind  stresses  on  the  lateral  systems  are  to  be  calculated 
for  a  moving  load,  instead  of  one  upon  the  whole  bridge  ;  because 
this  method  causes  the  rods  towards  the  centre  of  the  span  to 


IRACING. 

s  are  deter- 
;hrough  the 
^sure  on  all 
;  is  concen- 
plane  at  the 
u  nipt  ion,  or 
cr. 
ion  of  wind 

before,  the 
her. 

area  of  the 

:luding  hub 

about    the 

and  to  this 
of  the   floor 

under  high 
e.xcess  ;  but 

the  wind  is 
pans  of  and 
d  and  thirty 
'  determined 
would  make 
le  necessary 
rable  XXV. 
le  calculated 
Ige ;  because 
the  span  to 


o/wj.v.iA'i-  /AU)x  uicnwAv-nRincEs. 


49 


he  somewhat  increased  in  diameter  :  besides,  it  is  possible  for 
a  portion  only  of  a  structure  to  be  subjected  to  wind  pressure- 
the  rest  being  protected  by  a  hill,  a  building,  or  some  other 
neighboring  object. 

Without  making  any  appreciable  error,  the  wind  pressure,  for 
the  purpose  of  simplifying  calculation,  may  be  considered  as 
equally  distributed  between  the  two  sides  of  the  bridge,  althou-h 
the  windward  side  does  receive  the  larger  share.  " 

The  stress  in  any  diagonal  can  be  found  by  the  formula 
^  _  !i'(?i'  +  i)     7o  sec  e 

and  that  in  any  strut,  except  at  the  end  of  the  lower   lateral 
system,  by  the  formula 


C  = 


n\n  ~  \)  +  n 


271 


•70, 


wiiere  r.'  is  the  sum  of  the  pressures  at  a  wind 


lanel  point,  //  the  number  of  panels  in  th 


ing  in  the  two  lackiu";  at  th 


ivard  and  leeward 
e  wind  bracing,  count- 


e  ends  of  the  upper  lateral  brae 


m-r 


in  through  bridges, ;/  ("not  less  th 


lan 


D 


th 


e  number  at  the  lee- 


ward 


end  of  the  diagonal,  or  at  eitl 


panel  pom 


ler  end  of  the  strut,  the 
ts  being  marked  as  directed  in  the  last  chapter,  and 


't  the  angle  that  the  diagonals  make  with  th 

1  he  stresses  in  the  diagon 
tension,  or,  what  is  the  same 


e  struts. 


al 


s  are  to  be 


th 


increased  for  initial 


)e  taken  from  Tabic  IX. 


mg,  the  W(jrking-stresses  are  t 


0 


T 


atl( 


le  ellect  of  the  initial  tei 


led  to  the  stresses  in  those  member 


sions  on  the  struts  is  also 


to  bi 


The  method  of  calculating  the  st 


resses  in   the  vertical  sw 


bracing  is  as  follows.     It  is  essentially  that  of  Profe< 


;i\'en  in  his  treat 


In  1-ig.  I,  let  J'  be  the 


se  on  "  Stresses  in  Brids 


ay 
ssor  Burr,  as 
;eand  Roof  Trusses." 


at  the  upper  ])anel  point  on  on 


pressure  supposed  to  be  concentrated 


wliic'h  CO 


e  side  of  the  brid- 


mes   upon  a  panel   length   of  lop   chord, 


area  o|  the  diaironals 


:e'.      It   is  that 
one-haif  the 


tiun  of  the  post  above  the  plane  A/> 


meetmg  at  the  panel  point  and  th 


por- 


so 


OA'D/.V.I A"  1  •  /A'OA  I i lull II :n  -JIKJDGES. 


Let  P'  be  the  pressure  concentrated  at  one  end  of  the  inter- 
mediate strut /A'.  It  is  that  which  comes  upon  the  portion  of 
the  post  between  the  planes  AB  and   CD,  the  latter  passing 

halfway  between  the  intermediate  strut 
and  the  bottom  chords.  If  the  interme- 
diate strut  be  at  the  middle  of  the  post, 
and  if  the  main  diagonals  and  counters  be 
coupled  on  a  pin  at  this  point,  it  would 
be  necessary  to  divide  the  pressure  upon 
■  w**H  the  diagonals  between  the  upper,  middle, 
and  lower  points  of  the  posts ;  the  middle 
taking  one-half,  and  the  others  one-quarter  each. 

Let 

d  =  the  depth  of  the  truss, 

/=  the  vertical  distance  between  the  upper  lateral  and  interme- 
diate struts, 
d  =  the  perpendicular  distance  between  centres  of  trusses, 


and 


6  =  the  ancle  made  bv  the  vibration  rods  with  the  vertical. 


The  pressures  concentrated  at  the  lowest  points  of  the  posts 
do  not  affect  the  vertical  sway  bracing,  so  are  not  considered. 

The  total  pressure,  2{P  +  /")  =  //,  is  assumed  to  be  ec|ually 
resisted  by  the  feet  of  the  posts.  It  is  possible  that  this 
assumption  is  incorrect,  for  one  foot  may  resist  more  than  the 
other ;  but,  when  it  is  remembered  that  perhaps  the  whole  of 
the  force  2P  passes  through  the  upper  lateral  system  to  the 
pedestals  at  the  feet  of  the  batter  braces,  it  will  be  conceded 
that  the  assinnption  is  not  upon  the  side  of  danger. 

If  the  whole  of  2{P  -f  P')  were  to  be  resisted  by  the  feet  of 
the  posts,  th(!  functions  of  the  upper  lateral  system  would  be 
rather  limited,  the  whole  of  the  wind  pressure  upon  the  sliuc- 
ture  being  carried  by  the  lower  lateral  system,  which  is  highly 
improbable. 

But,  whether  the  wnnd  pressure  upon  the  upper  part  of  the 
trusses  be  carried  by  the  ujiikt  or  by  the  lower  lateral  bracing,  it 
is  better,  as  far  as  the  vertical  sway  bracing  is  concerned,  to  pro- 
portion the  latter  under  the  suj^position  that  the  pressures  at  the 
upper  panel  points  are  carried  thereby  to  the  feet  of  the  posts. 


ORDIXARY  IKOX  UIGHWAV-IiRlDGES. 


5' 


ral  and  interme- 


Taking  the  centre  of  moments  at  E,  the  moment  of  the 
pressure  is 

2Pd+  2P\d-f),  : 

which  can  be  resisted  only  by  the  moment  of  a  released  weight 
/'upon  the  foot  at /^;  thus, 

2Pd^2P\d-f)=.Vb, 

and 

y_2d{P^P')-2P'f 

b 

This  release  of  weight  V  must  pass  up  the  vibration  rod  KG, 
causing  a  tension  therein  equal  to 

,.        „       2d{P+  P')  -  2P'f 
Fsec 6  =  ^  ^' Z. sec 6, 

To  find  the  stress  on  the  strut /A',  pass  a  plane  through  the 
sway  bracing,  cutting  GI/,  GK,  and /A'  {///  not  being  strained); 
take  the  centre  of  moments  at  G,  and  consider  the  forces  act- 
ing on  the  left  side  of  the  truss ;  then  the  moment  of  the  stress 
In  JK  will  balance  the  moments  of  P'  and  i//,  thus, 


(Ml  = 


\Hd-P'f      d,^ 

^~^-^=jr{P^P')-P', 


to  which  must  be  added  the  horizontal  component  of  the  initial 
tension  in///.     {JK)  represents  the  stress  mJK. 

The  stress  in  the  upper  lateral  strut  GH  is  that  due  to  the 
wind  pressure,  considering  it  as  a  portion  of  the  upper  lateral 
system  plus  the  sum  of  the  horizontal  components  of  the  initial 
tensions  in  the  three  rods  meeting  at  one  of  its  ends. 

If  G/I  be  considered  as  a  portion  of  the  vertical  sway  bracing, 
its  stress  may  be  found  by  passing  a  jilane,  as  in  the  last  case! 
and  taking  the  centre  of  moments  at  K,  considering  the  external 
fcrces  acting  on  the  left-hand  half  of  the  truss ;  then  the  mo- 
ment of  the  stress  in  Gil  will  balance  the  moments  of  the 
horizontal  re-action  at  E  and  the  pressure  at  G,  the  moment 
of  the  increased  weight  at  E  balancing  the  moment  of  the 
increased  re-action  ;  thus, 

or  equal  to  the  stress  in /A". 


[ 


52  ORDINARY  IRON  HIGIIWAV-HRI IK;ES. 

At  first  thought,  it  might  appear  tliat  the  two  stresses  found 
for  GH  should  be  added  together  to  obtain  the  total  stress ;  but 
such  is  not  the  case,  for  the  wind  pressures  cannot  pass  by  both 
the  vertical  sway  bracing  and  the  upper  lateral  bracnig  :  so  the 
greater  stress  must  be  taken.  In  all  practical  cases,  the  greater 
stress  will  be  found  by  considering  GH  as  belongmg  to  the 
upper  lateral  system. 

The  bending  moment  on  the  post  is 

and,  if  m  be  the  distance  between  centres  of  gravity  of  post 
chamiels,  the  stress  on  one  channel  produced  by  the  bending 

^-  III 

The  released  weight  V,  on  the  windward  post,  passes  down  the 
leeward  post,  producing  a  stress  equal  to  y  on  each  channel, 
makinf^  the  total  wind  stress  on  one  channel 

According  to  the  method  given  in  Chapter  IV.,  if  twice  this 
stress  or  2C+  F,  exceed  the  live-load  stress  on  the  post,  mul 
tiplied  by  seven  and  a  half  {jV),  and  divided  by  the  intensity  ot 
working  tensile  stress  for  lower  chords,  the  post  must  be  pro- 
portioned for  dead-load  and  wind  stresses,  instead  of  dead-load 
and  live-load  stresses. 

All  these  formulas,  except  that  for  the  stress  in  GH,  may  be 
made  applicable  to  the  portal  bracing  by  putting  for  d  the  length 
of  the  batter  brace,  for  /  the  perpendicular  distance  between 
centre  lines  of  upper  and  lower  portal  struts,  for  /"  the  press- 
ure on  one-half  of  the  batter  brace,  and  for  P  one-fourth  of  the 
sum  of  all  the  pressures  concentrated  at  windward  and  leeward 
panel  points  of  the  top  chord. 

If  Pi  be  the  pressure  at  the  leeward  hip,  then  the  stress  on 
the  upper  portal  strut  will  be  Ldvcn  bv  the  formula 


C='^(r+P')-^"  +  ^'-P'' 


OKDIXARV  INOA  lllCllWAY-nRlDCES. 


53 


he  stress  on 


The  stresses  on  all  vibration  rods  must  he  increased  for  initial 
tension,  or  the  rods  must  be  proportioned  by  using  Table  IX.  ; 
and  the  stress  on  each  portal  strut  is  to  be  increased  by  the 
sum  of  the  components  of  the  initial  tensions  in  all  the  rods 
meeting  at  one  of  its  ends,  taken  in  the  direction  of  its  length. 

When  there  is  no  vertical  sway  bracing,  stiffness  is  obtained 
by  the  use  of  knee  braces,  or  brackets  {AB,  CD,  Fig.  2),  making 
angles  of  forty-five  degrees  with  the  vertical.  Let  the  notation 
be  as  shown  in  the  figure;  F  being,  as  before,  the  release  of 
weight  at  /-:     P  is  the  sum  of  the  pressures  at  H  and  G. 

Taking  the  centre  of  moments  at  E  gives 

b' 


Vb  =  Pd    and     V  = 


Again :  taking  the  centre  of  moments  at  A  gives  the  value  of 
the  bending-momcnt  J/ on  the  strut  at  that 
point  ;  thus, 

M=  V{b  -S)-  hPd=  ^'Ub  -  2S). 


G  k-S-- 

TV 

I- 

I 
I 

I 

I 
I 


—b 

Fig.2 


•»-.iP 


jr««.ip 


Let  //  equal  the  distance  between  the  cen 
tres  of  gravity  of  the  two  channels  of  which    j 
the  upper  lateral  strut  is  comi)osed,  then  the 
bcnding-stress  will  be 

^      M       P/ 
'^--k^.bl^'-^^^' 

The  intensity  of  the  working  bending-stress  being  six  tons, 
the  number  of  square  inches  to  be  added  to  the  area  of  each 
channel,  in  order  to  resist  bending,  will  be 

A       C        Pi  ,, 
A=  -=      ,,{b-  2S). 
6       1 2b/i  ^  ' 

The  stress  in  AB  is  found  by  taking  the  centre  of  moments 
at  G,  and  making  the  moment  of  its  stress  R  equal  to  the 
moment  of  the  horizontal  re-action  at  E  ;  thus, 


and 


RS\l\  =  \Pd, 
^  =  -^\h  =  0-707  ^.  • 


54 


OA'JJLV.lA'y  /A'O.V  lHullWAV-BRUhiES. 


As  before,  to  make  these  formulas  applicalile  to  a  portal, 
make  d  equal  to  the  length  of  the  batter  brace,  and  P  equal  to 
one-half  the  sum  of  the  pressures  concentrated  at  all  the  upper 
panel  points  of  the  bridge. 

To  find  the  effect  of  the  wind  on  posts  and  batter  braces, 
use  the  formula  previously  found,  substituting  in  it  .S'  for  /. 

Finally,  the  stress  in  an  end  lower  lateral  strut,  at  the  free 
end  of  the  span,  may  be  obtained  by  the  formula 


C„  = 


2« 


•IV 


+ /cos  6 + '-^ .  w'  -  \  (^-  -  vy 


where  ;/  is  the  number  of  panels  in  the  bridge,  tc  the  sum 
of  the  windward  and  leeward  panel  wind  loads  for  the  lower 
system,  re-'  the  same  for  the  upper  system,  /  the  initial  tension 
in  the  end  lower  lateral  rod,  $  the  angle  between  this  rod  and 
the  strut,  fCthc  total  weight  of  the  unloaded  bridge,  and  /'the 
release  of  weight  at  a  windward  shoe. 

Owing  to  the  fact  that  the  joists  of  the  end  panel  rest  on  the 
masonry,  this  formula  will  give  a  result  slightly  on  the  side  of 

safety. 

One  or  two  applications  of  this  formula  will  convince  the 
most  sceptical,  that  the  general  idea  that  any  section  is  strong 
enough  for  a  strut  between  pedestals  is  a  fallacy.  Too  great  a 
reliance  has  hitherto  been  placed  upon  the  friction  of  the  shoe, 
the  released  weight  there  not  having  been  considered  ;  and  the 
pressure  which  comes  from  the  upper  panel  points  seems  to 
have  been  neglected. 


ORDhXARV  IROiX  HIGHIVAV-URIDGES. 


55 


CHAPTER  VII. 


REMARKS   CONCERNING   MAIN   MEMBERS. 


Top  chords  should  nearly  always  be  built  of  two  channels, 
will)  a  plate  on  top,  and  latticing  or  lacing  below.  It  is  never 
good  practice  to  use  a  single  I-beam  for  top  chord  or  batter 
brace,  because  of  the  great  variation  in  stiffness  in  its  two 
])rincipal  rectangular  jilanes  and  the  difficulty  in  making  neat 
details  for  the  connections.  When  the  s|)an  iDecomcs  so  short 
that  it  appears  to  be  economical  to  use  such  a  section,  it  is  short 
enough  to  employ  plate  girders  which  are  far  superior,  both  as 
regartls  strength  and  stiffness,  to  a  bridge  with  I-beam  chords. 

The  same  objection  applies  to  an  I-beam  post,  a  favorite 
design  of  inferior  bridge  companies.  If  one  were  to  take  the 
trouble,  in  passing  over  a  few  bridges  where  they  are  used,  to 
cast  his  eye  along  the  posts,  he  would  generally  see  that  they 
are  bent  to  one  side  or  the  other,  or  to  both  ;  the  latter  being 
the  case  when  there  are  employed  what  are  termed  out  West 
"(}iasticutus  rods,"  or  horizontal  rods  five-eighths  or  three- 
quarters  of  an  inch  in  diameter,  passing  from  the  middle  of  one 
post  to  the  middle  of  the  ne.\t  in  the  same  truss.  Such  rods 
are  a  noticeable  feature  in  arch  bridges,  a  class  of  structure  that 
ought  to  be  universally  condemned.  The  principal  objections 
to  these  bridges  are  their  lack  of  rigidity,  and  their  inability  to 
resist  wind  pressure,  because  of  the  absence  of  efficient  lateral 
bracing.  But  another  grave  fault  is,  that,  being  as  a  rule  built 
by  companies  of  the  low(}st  order,  they  are  weak  in  section  and 
detail,  and  the  workmanship  is  poor.  They  are,  without  doubt, 
the  cheapest  kind  of  iron  bridge  that  can  be  manufactured  : 
hence  their  general  adoption  throughout  the  West,  where  short- 
sighted economy  in  building  is  the  order  of  the  day. 


5<5 


OKDIA'ARV  ll<iK\   IllullU  AV-liRlih.F.S. 


The  I-hcani  is  mort- (iftcn  found  in  u,ij)er  laU'nil  struts,  wf^oiL' 
its  use  is  fjuitc  asobjcctioiiahlc,  ICvcn  if  strong  enough,  whirh 
it  .sekloni  is,  il  i-  by  no  means  tlie  hes*  section  for  that  place, 
owing  to  the  ditVuuUy  in  connecting  to  the  t  i])  cho  Wli   re 

it  rests  on  the  cliord  plate,  and  is  riveted  thereto,  the  lateral 
rods  being  attached  to  the  chord  pins,  there  is  a  great  leverage 
affcrded  to  the  wind  stresses  to  distort  tl\e  chord  ;  and,  where 
connected  to  the  [liii  by  a  jaw,  the  detail  I; as  to  be  either  very 
clumsy  or  very  weak.  Anothei  objection  to  I-beams  tor  lat(  ral 
struts  is  the  little  room  which  there  is  in  the  flanges  lur  innuh- 
ing  rivet  holes.  Hut  the  chief  one  is  the  small  resistance  tliat 
they  oft\  I  to  the  iieiiding  effect  of  the  wind  pressure  when  there 
is  no  vertical  sway  bracing.  \Vh..t  lias  been  said  of  I-beams  in 
lateral  struts  can  be  said  with  nui.eli  more  effect  concerning 
I-beams  in  i)ort:d  braces,  for  great  stiffness  and  strength  are 
there  necessary  in  order  to  carry  the  wind  pressure  upon  the 
upper  half  of  the  bridge  to  the  foundations. 

The  proper  function  oi  an  I-beam  is  to  resist  deflection  in  the 
plane  of  its  web:  ct)nset|uently  it  should  be  used  as  a  floor 
beam,  in  which  place  its  depth  should  seldom  be  less  than  ten 
inches,  never  less  than  nine  inches.  When  one  is  debating  about 
using  such  small  floor  beams,  he  should  ligure  them  for  a  eon- 
centratetl  wheel  load,  as  well  as  for  a  uniformly  distributed  load. 

About  the  only  places  where  a  small  I-beam  can  be  legiti- 
mately employed  are  between  the  i  edestals,  as  a  lateral  strut 
at  the  fi.xed  end  of  a  span,  or  at  the  free  end  if  the  bridge  be 
narrow  and  the  span  very  short,  and  in  vertical  sway  bracing  as 
an  intermediate  strut. 

For  upper  lateral  struts,  iron  gas-pipe  was  formerly  often  em- 
ployed, and  is  so  yet  to  a  certain  extent.  Regarded  as  a  section, 
nothing  could  be  better  fir  more  economical ;  but  the  connec- 
tions made  with  il  are  very  weak.  Then,  again,  there  is  the 
objection  that  it  is  a  closed  column,  and  consequently  inacces- 
sible to  painting.  Notwithstanding  the  fact  that  two  of  the 
leading  bridge  companies  of  the  I'nited  States  employ  almost 
exclusively  closed  columns,  such  columns  are  not.  by  engineers 
in  general,  conceded  to  be  so  good  as  open  ones,  which  are 
always  accessible  to  the  paiiU-brush. 


Sonic  other  common  forms  of  upper  lateral  struts  are  the  fol- 
lowing: two  tee-irons  trussed,  the  upper  restin-  on  tiie  ehorcis 
an<l  riveted  thereto,  the  low.r  ahuttin-  a-ainst  the  same  and 
att.KiK-d  by  bent  phites  ;  two  Uiannels  trussed  and  attachc'd  to 
thr   .hords  m  tlie  same  manner;  a  eomi)ination  of  a  channel 
and  a  plate,  with  trussing  between  ;  and  two  tee-irons  laced  or 
latticed,  with  a  jaw  plate  at  each  end  wider  than  their  flan-es 
screwed  up  to  the  chords  by  nuts  on  the  ends  of  the  chord  ptns' 
('win-  to  their  lack  of  both  strength  and  rigidity,  all  these  are 
|M.wr  contrivances,  two  channels  laced  or  latticed  bcin"-  the  best 
lorm  of  strut  that  can  be  designed  for  the  upper  lateral  system 
As  stated   in  the  "General   Specifications,"  in  no  highway 
bridge  should  the  channels  in  chords,  posts,  or  batter  braces  be 
less  than   live  inches  in  depth,  nor  in  any  other  part  of  the 
sti  urture  less  than  four  inches.     One  does  hear  occasionally  of 
such  a  thing  as  a  three-inch  channel  top  chord  with  tuo-inch 
I  Mils,  for  a  sixty  ur  seventy  foot  span.     JJut,  fortunately  for  the 
public  .safety,  such  structures  are  few  and  far  between      The 
author  once  heard  the  senior  representative  of  one  of  the  most 
llnunsh.ng  highway-bridge  companies  in  America  contend  that 
iwo  thice-mch  channels  trussed  make  a  very  good  centre  post 
lor   short    through-spans, -strong   enough,   because   the  area 
called  for  by  the  stress  is  less  than  three  square  inches      He 
must  either  have  forgotten,  or  been  ignorant  of,  the  f  ict  that 
stillness  IS  as  important  a  factor  in  a  bridge  as  simple  strength 
in   reality,   strength  is  dependent  upon  stiffness;    for  where 
vibrat  on  can  occur,  the  stresses  are  increased,  not  only  in  the 
members  where  stiffness  is  wanting,  but  in  adjoining  members 
of  the  structure. 

Light  sections  for  compression  members  arc  more  economical 
than  heavy  ones,  and  it  is  generally  preferable  to  use  them 
nut,  It  the  situation  be  one  where  the  members  will  be  exposed 
to  excessive  moisture,  the  webs  should  be  thickened 

1  he  top  plate  for  chords  and  batter  braces  should  generallv 
I'c  from  one-quarter  to  three-eighths  of  an  inch  thiJk.  Any 
thing  below  the  inferior  limit  would  be  liable  to  distortion  when 
roughly  handled,  and  to  ru.st  through  too  readily;  and  any  thino- 
above  the  superior  limit  would  usually  be  inconsistent  with  the 
best  distribution  of  area  in  the  section. 


58 


(>A'/>/.v.iA-y  /A'o.y  ///(/////'./ J -/m'/m;a\v. 


It  used  to  1)0  customary,  and  tho  practice  is  still  followed 
to  some  extent,  to  make  the  top  plate  of  varying  thickness,  or  to 
vary  the  number  of  plates,  increasin;,^  from  the  ends  of  the  truss 
to  the  centre,  makini;  the  ehanncls  of  the  same  dimensions 
throughout.  lUit  this  method  is  not  advisal)le  ;  for  the  proper 
plAce  for  the  larger  part  of  the  material  in  a  chord  like  the  one 
under  discussion  is  in  the  channels,  and  not  in  the  plate.  Simi- 
larly, in  any  channel,  the  proper  i)lace  for  the  larger  part  of  the 
material  is  in  the  flanges,  and  not  in  the  web;  the  reason  being, 
in  both  cases,  that  the  moments  of  inertia  of  the  section  in 
respect  to  vertical  and  hoiizontal  neutral  a.xes  are  increased  Iv, 
removing  a  portion  of  the  area  away  from  these  a.xes,  and  the 
strength  of  a  strut  increases  with  the  moments  of  inertiii  of  its 
section. 

Star  iron  should  never  be  employed  in  an  iron  bridge,  and 
there  is  never  any  necessity  for  using  tee-iron.  Two  of  the 
latter  sections,  latticed  by  a  triple  or  quadruple  intersection  ot 
thin,  narrow  bars,  are  sometimes  ado])ted  for  a  portal  brace  ; 
but  it  is  evident  how  weak  such  a  strut  must  be,  and  it  is  in 
the  very  place  where  a  strong  one  is  most  needed. 

Four  angles  with  the  legs  turned  in,  and  set  at  the  corners  of 
a  .square,  laced  on  the  four  faces  thus  formed,  make  an  economi- 
cal strut,  as  far  as  the  section  is  concerned  ;  but  it  is  probable 
that  the  e.xtra  weight  of  detail  and  the  increased  cost  of  shoii- 
work  will  make  it  more  expensive  than  another  strut  of  larger 
section.  Two  channels  latticed  or  laced  arc  the  best  form  of 
portal  strut.  Large,  heavy  cast-iron  [jortals  made  in  one  or 
two  pieces  look  very  well,  and  might  be  made  strong  enough, 
but  are  not  so  neat  and  graceful  as  some  other  kinds  of  bracing, 
besides  adding  unnecessary  dead  load  to  the  structure.  Cast- 
iron  is  not  to  be  depended  upon,  and  should  not  be  used  in  any 
part  of  an  iron  bridge  to  resist  stress. 

Channels  in  posts  usually  have  their  webs  parallel  to  the  direc- 
tion of  the  plane  of  the  truss,  with  their  flanges  turned  outward  : 
sometimes  they  are  turned  inward  ;  and,  where  the  floor  beams 
are  riveted  to  the  posts,  the  webs  are,  or  should  be,  placed  at 
right  angles  to  the  plane  of  the  truss,  the  flanges  turning  out- 
ward. 


0A'/)/.\:tA' y  /A'OA'  maun '.-/  j ■-uridgi-is. 


<;cv 


Theoretically  it  is  more  economical,  as  far  as  the  area  <.f  the 
>,eiti()n  is  concerned,  to  tuin  the  flanges  in,  for  the  moment 
of  inertia  is  greater;  but,  on  the  other  hand,  the  diiriculty  en- 
countered in  riveting  in  a  confined  space  more  than  equalizes 
tile  advantage  just  mentioned. 

Another  advantage  which  can  be  claimed  for  channels  turned 
in,  \\/..,  avoiding  cutting  them  off  before  reaching  the  upper 
rhord  pin,  is  partially  counterbalanced  by  the  increased  size  of 
pill,  due  to  the  larger  leverage  thus  given  to  the  stresses  in  the 
diagonals.  Notwithstanding  the  difficulty  in  riveting,  it  is  often 
hiuiid  necessary,  in  swing  bridges,  to  turn  in  the  flanges  of  the 
post  channels  in  order  to  form  a  good  connection  with  the  chan- 
iiel  bottom  chords  :  otherwise,  the  channels  of  the  bottom  chords 
may  be  turned  in,  and  the  post  channels  be  allowed  to  bestride 
tlicm. 

The  objection  to  cutting  away  the  flanges  of  channels  at  the 
feet  of  posts  has  been  shown  by  some  experiments  made  by 
the  Chicago  and  Alton  Railroad  Company,  as  given  in  a  paper 
i\a(l  before  the  Western  Society  of  luigiiieers  by  Air.  \\.  J. 
Ward,  who  shows  that  this  cutting-away  reduces  the  strength 
of  the  strut  about  ten  per  cent. 

Main  diagonals,  as  will  be  demonstrated  in  Chapter  X.,  should 
have  the  proi)()rlion  of  width  to  depth  of  about  one  to  four; 
and  the  chord  bars,  the  proportion  of  from  one  to  four  to  one 
to  seven,  according  to  the  number  of  them  in  the  panel. 

It  is  preferable,  for  ajipearances,  to  make  the  counters  of 
square  or  round  instead  of  flat  bars,  because  of  the  unsightly 
change  that  there  would  be  in  the  diameter  of  the  flat  bars  at 
the  upset  ends.  It  is  immaterial,  except  for  the  effect  upon  the 
pins,  whether  the  hip  verticals  be  flat,  scpiare,  or  round  ;  but 
the  preference  is  usually  given  to  square  iron. 

I5uilt  floor  beams  in  ordinary  bridges  should  be  formed  of 
solid  plates  and  angles,  and  not  made  trussed  ;  because,  even  if 
the  latter  method  permit  of  a  saving  of  material,  it  is  more 
conducive  to  vibration.  Where  the  panels  are  long  and  the 
roadway  is  very  wide,  it  would  be  permissible  to  use  trussed 
!)L'ams,  provided  that  they  be  made  \ery  rigid  in  their  details, 
and  not  too  slight  in  their  .sections. 


i;;  ! 


CO 


C'A'/V 


.y.i/n'  iNox  ]iic,iiw.\y-Bi^ii)C,Es. 


CHAPTER  VIII. 

rUOrORTIONING    OF    MAIN    MKMBKRS    OK    TRUSSES.    LATERAI 
SYSTEMS,   AND    SWAY    ISKACIXo. 

HwixG  found  all  the  stresses  in  the  main  members  of  the 
truss  and  in  those  of  the  lateral  systems  and  sway  bracmg,  and 
havino-  written  them  alon-side  the  respective  members  m  the 
dia-n-mns,  the  next  step  is  to  calculate  the  sections  requn-cd. 
The  dia-rams  for  the  lateral  systems  and  sway  bracmg  may  be 
rouohly\u-awn  in  pencil  ;  for  they  need  not  be  preserved,  as  the 
size's  of  the  members  are  to  be  written  on  the  truss  dia-ram. 

For  the  tension  members  of  the  trusses,  the  sections  required 
can  be  found  by  dividing  the  stresses  on  the  diagram  by  the 
proper  intensities  of  working-stress,  as  given  on  p.  12;  remem- 
bering- that  the  intensities  for  main  diagonals  are  to  be  inter- 
polated. When  f.u.ncl.  the  reciuired  areas  for  the  sections 
should  be  written  on  the  diagram,  after  the  stresses,  preuxing 
them  with  the  letters  S.  R.  (section  required),  as  shown  on 
riue  V  Then,  by  using  Carnegie's  "  Pocket-Companu).. 
pp.  94-105,  or  some  eciuivalent  tables,  ^an  be  found  the  sizes 
necessary  to  give  at  hast  the  section  required,  taking  care  that 
the  sections  be  in  good  proi«)rtion. 

The  stresses  in  the  counters  are  to  be  increased  for  initial 
.crsion  by  the  amounts  given  on  p.  10;  or,  what  is  the  same 
tliin.^  the  size  required  can  be  found  from  Table  IX.  by  look- 
ing-'";iown  the  column  headed  "  Working-Stress  =  4  tons  per 
.c,uaie  inch,"  if  the  bridge  belong  to  Class  A,  or  down  the  one 
headed  "  Working-Stress  =  5  tons  per  square  inch,  if  it  belon.i; 
to  Class  W  or  Class  C",  until  a  stress  is  reached  which  is  ec|ual 
to  or  greater  than  one-half  or  the  whole  of  the  .stress  on  the 


diuo-ram,  according  to  whctlier   doul)le  or   single   counters 


:)C 


Oh'D/.y.iRv  /A'o.y  }ii<.;iiivAY-nRii)(.]Es. 


6 1 


ES,    LATER  A I 


cniplincd  ;  tlicn,  by  following;-  the  horizonla!  line  which  con- 
tains tliis  stress,  cither  to  right  or  left,  will  be  found  the  ^ize 
of  the  counters  or  counter  required. 

As  previously  mentioned,  the  sections  required  for,  and  the 
sizes  of,  the  hip  verticals,  can  be  found  without  calculation  from 
OIK-  of  Tallies  VI.,  VII.,  or  VHI.  Should  the  joists  and  floor- 
ing,' be  of  oak  instead  of  pine,  the  section  required  for,  and  the 
<ize  of,  hi])  verticals,  can  still  be  found  from  the  table  by  sup- 
posing an  increase  of  one  foot  in  the  panel  length. 

The  sizes  of  the  lateral  and  vibration  rods  can  be  found  from 
Table  IX.  by  looking  in  the  column  headed  "Working-Stress 
=  7-5  toii^  P^'f  square  inch,"  in  the  same  manner  as  e.xplainetl 
for  counters.  If  the  panel  length  correspond  with  the  one  given 
in  Table  IV.,  or  if  it  do  not  differ  greatly  therefrom,  there  need 
be  no  calculations  made  for  stresses  in  the  lateral  .systems  and 
sway  bracing  ;  for  the  dimensions  of  all  the  struts  and  rods  for 
these  .systems  are  given  in  Table  XXV.  In  that  table  the 
(iimcnsions  in  the  column  marked  "  Pan.  i  "  arc  the  sections 
rcsi)ectively  of  the  upper  portal  struts,  the  portal  vibration  rods 
df  any),  the  lower  portal  struts  (if  any),  and  the  end  lower  lat- 
eral rods.  Those  in  the  other  columns  are  the  sections 
resiK'ctively  of  the  upper  lateral  struts,  the  upper  lateral  rods, 
the  post  vibration  rods  (if  any),  the  intermediate  struts  (if  anv), 
and  the  lower  lateral  rods.  The  portal  struts  are  thus  assumed 
to  belong  to  the  first  panel ;  the  first  upper  lateral  strut,  with 
its  sway  bracing,  to  the  second  panel,  etc.  ;  so  that,  when  the 
bridge  has  an  odd  number  of  ijanels,  there  is  no  lateral  strut 
or  vertical  sway  l)racing  given  for  the  middle  panel.  The  fort\- 
toot,  fifty-foot,  and  si.\ty-foot  span.^,  being  pony  trusses,  have 
only  lower  lateral  rods.  Sloans  above  one  hundred  and  fift)' 
feet  in  length  have  \ertical  sway  bracing. 

If  the  counter  stresses  be  large,  it  is  preferable  to  use  double 
counters :  sometimes  both  single  and  double  counters  are  cm- 
plt.yed  in  the  same  truss.  Where  there  is  an  odd  number  of 
]xuiels,  the  centre  tliagonals  should  be  made  double  and  adju.sta- 
hle.  The  number  of  main  diagonals  per  panel  is  generally  two  ; 
init,  if  the  sections  become  so  great  as  to  necessitate  excessively 
large  chord  pins,  it  is  better  to  employ  f.iur  ;  placing  two  inside, 


02 


OKD/X.UiV  INOX  HIGHWAY-BRIDGES. 


and  two  outside,  of  the  top  chord  and  posts.  The  widths  of  the 
main  diagonals  should,  for  the  sake  of  appearance,  increase 
from  the  centre  of  the  bridge  to  the  ends.  For  the  same  rea- 
son, it  is  well  to  have  all  the  chord  bars  of  the  same,  or  nearly 
the  same,  depth  ;  the  correct  area  of  section  being  obtained  for 
each  panel  by  varying  the  thickness  and  the  number  per  panel. 
In  large  bridges  it  is  permissible  to  reduce  the  depth  of  the 
choid  bars  towards  the  ends  of  the  span  in  order  to  economize 
on  the  pins.  It  is  also  permissible,  when  there  are  several 
chord  bars  in  the  same  panel,  to  employ  depths  varying  by  a 
quarter  of  an  inch,  provided  that  the  bars  of  smaller  depth  be 
placed  on  the  inside. 

As  stated  in  the  "  General  Specifications,"  where  chord  bars 
are  trussed  to  resist  the  buckling  effect  of  the  wind  pressure, 
the  intensities  of  working-stress  for  the  trussed  bars  on  the  net 
section  should  be  reduced  to  four  tons  for  bridges  of  Class  A, 
and  to  five  tons  for  those  of  Classes  B  and  C. 

"Chord  packing"  is  a  term  applied  to  the  arrangement  of  the 
chord  bars,  diagonals,  posts,  and  beam  hangers  upon  the  bottom 
chord  pins.  It  is  a  matter  of  great  importance,  but  is  very 
often  neglected.  The  three  princijial  considerations  to  be  kept 
in  mind  while  arranging  the  packing  are,  that  the  bending- 
moments  on  the  pins  are  to  be  made  as  small  as  possible,  that 
the  packing  is  to  be  made  as  close  as  circums;ances  will  permit, 
and  that  there  be  sufficient  clearance  to  avoid  all  chance  of 
finding  the  space  between  the  post  channels  too  narrow  when 
the  bridge  is  being  erected. 

The  width  of  the  packing  is  dependent,  not  only  upon  the 
number  and  thickness  of  the  bars,  but  also  upon  the  width  of 
the  top  chord  plate.  The  latter  is  often,  in  its  turn,  dependent 
u]X)n  the  chord  packing. 

Th<'  usual  arrangement  is  to  pack  the  main  diagonals,  coun- 
ters, and  beam  hangers  inside  of  the  posts,  and  the  chord  bars 
outside  ;  bringing  the  latter,  however,  within  the  batter  braces 
at  the  shoes,  unless  the  end  panel  contain  four  bars  per  truss, 
when  two  should  go  outside,  and  two  inside.  It  is  not  abso- 
lutely necessary  that  the  chord  bars  \m\\  in  the  exact  line  of 
the  trusses  ;  an  inch  or  two  of  deflection  in   twenty  feet  being 


ORDINARY  IROX  lilGHW AY-BRIDGES. 


0?> 


scarcely  noticeable,  and  making  no  appreciable  difference  in  the 
length  of  the  bar :  nevertheless,  it  is  better  to  make  the  bars  as 
nearly  as  possible  parallel  to  the  planes  of  the  trusses.  The 
main  diagonals  should  be  placed  next  to  the  post,  then  the 
beam  hangers,  and  inside  of  all,  the  counters  with  a  filler 
iK'tvveen  them  long  enough  to  permit  of  the  screwing-up  of  the 
turn  buckles,  or  sleeve  nuts. 

The  arrangement  of  the  chord  bars  will  be  treated  in  Chan- 
ter  X.  ^     * 

The  sections  of  the  top  chords  and  batter  braces  are  to  con- 
sist of  two  channels,  with  a  plate  on  top,  and  latticing  or  lacing 
below.  The  same  depth  of  channel,  and  the  same  width  and 
thickness  of  plate,  are  to  be  employed  from  one  end  of  the  chord 
t.)  the  other;  the  difference  in  area  being  obtained  by  thicken- 
in-  the  webs  of  the  channels.  On  this  account,  there  is  often 
an  excess  of  section  in  the  end  panels  of  the  top  chord,  and,  in 
long  bridges,  even  in  the  next  panels. 

It  is  customary  and  better,  but  not  necessary,  to  make  the 
depth  of  the  channels  in  the  batter  braces  the  same  as  that  of 
the  channels  in  the  chord.  Tlie  top  plate  for  the  batter  brace 
should  be  of  the  same  size  as  that  for  the  chord. 

The  width  of  the  toji  plate  is  dependent  upon  the  depth  of 
the  channels ;  as  the  transverse  distance  between  the  centre  lines 
of  the  rivets  which  attach  the  channels  to  the  plate  should  be 
never  less,  and  not  (unless  there  be  good  reason)  much  greater, 
than  the  depth  of  the  channels.  The  least  dimensions  for  such 
|)lates  for  different  channels  are  given  on  p.  15,  The  chord 
channels  are  sometimes  spread  apart  in  pony  trusses,  so  as 
to  mcrease  the  lateral  stiffness;  and  in  any  bridge  it  may  be 
necessary  to  spread  them  a  little  to  admit  of  a  certain  manner 
of  packing  below :  but,  the  more  narrow  the  chord  plate,  the 
more  economy  of  material  will  there  usually  be. 

To  proportion  the  top  cliord  or  batter  brace  for  a  given  stress, 
.issume  the  deplh  of  the  channels,  and  divide  the  length  of  the' 
piiiel  or  batter  brace  by  it,  both  dimensions  being  expressed  in 
the  same  unit.  Referring  to  Table  X.  or  XI.,  according  to  the 
class  of  bridge  to  be  designed,  look  down  the  column  marked 
"Kutioof  L  to  A"  until  the  ratio  ju.st  found  is  reached:  the 


64 


ONJ)L\AKy  JA'iKV   J/lu/IUW  ) -/.'A7/n;/'-.V, 


n 


umber  to  the  ri<rht,  in  the  first  of  the  three  columns,  is  the 


s  are 


intensity  of  working-stress  to  be  used.  The  three  column 
for  the  three  cases,  —  both  ends  fixed,  one  end  fixed  and  one 
end  hinged,  and  both  ends  hinged,  marked  LiE,  L^iO,  and  (•• 
respectively.  The  tables  were  calculated  by  the  formula  of 
C.  Shaler  Smith,  CM.  ;  to  whom  the  author  is  indebted  for 
its  use,  and  for  other  valuable  information  in  connection  with 
bridge  work.  Then,  to  find  the  area  of  the  top  chord  or  batter 
brace,  divide  the  stress  given  on  the  diagram  by  the  intensity 
of  working-stress  taken  from  the  table ;  from  the  quotient 
subtract  the  area  of  the  top  plate,  and  divide  the  remainder 
by  two  :  the  final  quotient  will  be  the  area  of  each  channel. 
This  calculation  should  be  made  with  both  the  stress  in  the 
panel  nearest  the  middle  of  the  span  and  that  in  the  end 
one,  or,  in  long  spans,  that  in  the  one  next  to  the  end.  If, 
then,  with  the  depth  of  channel  assumed,  it  be  found  that 
there  is,  in  the  taljle  of  channel  sections  employed,  a  light 
channel  that  will  not  be  much  too  heavy  for  the  end.  and  a 
table  for  the  middle  of  the  chord,  all  right  : 
ther  trial   must   be  made,  with  a  channel  of  a   dif- 


leavier   one   sui 


if  not. 


ano 


fcrent  depth.  The  greater  the  depth  of  channel,  the  less 
the  ratio  of  length  of  strut  to  diameter,  and  consequently 
the  greater  the  intensity 
sectional  area  required  :    : 


)f   workinu-stress,  and  th( 


less 


generally  speakin; 


use    the    lightest    and    deepest    channel;-:    possible, 
saving  in  section  be  small,  when   it  will  be 


the 

it    is   well    to 
unless    the 


more  econonucal 


for  other  reasons,  to  use  the  next  smaller  depth.     These  rea- 
sons will   be  given  in  Chapter  XV.      The  dimensions  of  the 


channels 


an 


d    pi 


ate    should    be    written    on    the    cHagram    of 


stresses  as  shown  on   Plate  V. 

The  sizes  of  the  post  channels  are  to  be  found  in  a  similar 
manner  to  the  one  just  described,  with  these  two  exceptions, — 
that  the  column  for  two  hinged  ends  i  to  he  used,  and  that 
there  is  no  plate.  .Some  engineers  prefer  fixing  the  uj)])er  ends 
of  the  i)osts  bv  attaching  them,  through  the  medium  of  pkites. 
to  the  chord,  thus  saving  a  little  in  the  section  ;  but,  as  will  be 
seen  farther  on,  there  is  no  true  economy  in  so  doing. 

In  high  double-intersection  bridges,  where  the  diagonals  are 


OKD/A.INV   /A'OX  IIIC.n\VAV-I^R,nGKS.  65. 

halved  and  connected  by  pins  passin-^  through  the  middle  of- 
he  post  channels,  as  shown  in  Fi.-.  ,5.  Plato  [I.,  the  post  may 
be  proportioned  for  half-length  witl,  both  ends  hinged;  but  in 
this  case  the  counters  must  extend  to  the  ends  of  the  span 
although  there  be  no  stress  in  some  of  them,  for  the  purpose  of 
preventing  the  posts  from  moving  laterally  at  the  middle     " 

The  upper  lateral  struts  and  portal  struts  are  to  be  propor- 
t.oned  by  using  Table  XI.  for  both  ends  fixed,  and  adiing,  f 
necessary,  to  the  section  thus  found,  enough  area  to  resist  the 
bending  as  determined  in  Chapter  VI 

The  ultimate  strength  of  the  intermediate  struts,  which  are 
Ibcams  can  generally  be  found  from  experiments  made  by  the 
manuaicturers  ;  a  factor  of  safety  of  four  being  sufficient      In 
default  of  such  experiments,  the  approximate  workino-.stresses 
^:^^^^^^^  foi-Lbeams  used  as  pillars  may  be  ta^:;  f::m 
iablc  XL.,  which  has  been  compiled  from  an   old  edition  of 
Carnegie  s  "Pocket-Companion."     When    the  I-beam   .strut 
suppo,sed    o  bend  ,n  a  vertical  plane,  its  length  should  be  taken 
c<,u     to  the    istance  between  the  points  of  attachment  of  th 
-a     ets     but  when  ,t  ,s  assumed  to  bend  in  a  horizontal  plane, 
.ts  cngth  mu.st  be  taken  equal  to  the  distance  between  opposite 
posts  of  the  trusses.  i^pposut 

J^rackets  should  extend  inward  and  downward,  from  about 
l<n,r  feet  m  narro^v  bridge  s,  to  about  six  feet  in  wid;  ones  it 
s|.,ybrac,ng  given  in  labie  XXV  was  proportioned  for  brack- 
a  of  hese  dimension,s.  Brackets  beneath  intermediate  struts 
n^onb^rvetostiH^^^ 

Ti-  intermediate  lou.  r  lateral  struts  being  of  wood,  it  will 
n.H   be   necessary  to  calculate  their  section.s,   which  p  actical 

;;;;-c..uo. 

'  SI,  t  of  two  channels  laced  or  latticed,  and  ■  ttached  to  the 
'"'  ;'7'  P.ns  by  J,,..      The  si.e  for  the  channels  is  to     e 

-       lut   utl.er  end  is  really  fixed  or  hinged,  but   I^cause  the 
■^tungth  of  a  strut  .0  attached  is  intermediate  between  that  of 


66 


ORl)/XARy  JA'-'-y  JiIOJIUA)-!lJ</D'^ES. 


one  witii  fixed  ends  and  that  of  one  with  hinged  ends.  It  is 
not  positively  necessary  to  use  a  lateral  strut  at  the  fixed  end 
of  a  span  ;  but  it  is  much  better  to  do  so,  especially  in  long 
spans,  not  only  to  distribute  the  horizontal  re-actions,  but  also 
to  keep  the  chords  in  line,  for  there  is  necessarily  a  little  play 
in  the  anchor  bolt  holes. 

It  is  not  unusual  to  make  the  struts  between  pedestals  of  the 
same  dimensions  at  l)oth  ends  of  the  span,  although  the  one  at 
the  fixed  end  need  not  be  so  strong  as  the  one  at  the  free  end. 
Appendix  I.,  the  substance  of  which  appeared  as  an  editorial 
in  the  "  American  Engineer"  of  July  20,  1883,  shows  the  neces- 
sity for  stiffening,  at    least   the   end  panels  of  many  bottom 
chords.     This  can  be  accomplished   in  several  ways;  one  by 
inserting  a  strut  between  the  inner  chord  bars  ;   another  by 
using  channel  bars,  laced  or  latticed,  instead  of  eye  bars,  in 
which  case  the  net  section  of  the  zvcbs  alone  should  be  relied 
on  to  resist  tension  ;  and  another  by  trussing  the  inner  chord 
bars.     The  second  of  these  methods  is  the  most  satisfactory, 
but  at  the  same  time  the  most  expensive.     When  stiffening 
the   end    panel,   it   is   well,   though   not   perhaps    essential,    to 
stiffen  also  the  second  panel,  where  the  stress  is  the  same  as 
in  the  one  at  the  end.     Such  a  practice  is  certainly  conducive 
to  the  prevention  of  vibration  of  light  bridges  under  rapidly 


moving  loads. 


Hip'^vcrticals  in  three  or  four  panel  pony  trusses  are  to  be 
made  to  resist  the  compression  which  might  be  produced  m 
them  by  rA-er-screwing  the  turn  buckles  of  the  counters.  The 
section  to  be  employed  is  cither  that  of  two  channels  laced  or 
latticed,  or  two  flat  bars  trussed  :  in  the  latter  case,  as  iire- 
viously  stated  in  the  "General  Specifications,"  the  intensities 
of  working  tensile  stress  on  the  net  section  are  to  be  three  tons 
for  bridges  of  Class  A,  and  four  tons  for  bridges  of  Classes  15 
and  C.  If  two  channels  be  used,  the  net  area  of  the  webs  alone 
is  to  be  relied  on  to  resist  tension. 


ORDINARY  IRON  UHJUlVAY-BRIDuES. 


6; 


CHAPTER   IX. 

PROPORTIONING   OF   FLOOR   SYSTEM. 

The  wooden  portions  of  the  floor  system  are  the  joists,  floor- 
ing, hand  railing,  hub  planks,  and  guard  rails,  or  felly  planks. 
Of  these,  only  the  joists  require  calculation  for  strength  Pine 
flooring  is  generally  three  inches  thick,  and  oak  flooring  two 
and  a  half  inches.  The  hand  railing,  when  of  wood,  should 
consist  of  4"  X  6"  X  4'  posts,  not  more  than  ten  feet  apart 
2"  X  6"  rails,  and  2"  X  12"  hub  plank,  all  of  pine,  and  built  as 
shown  m  Plate  II.,  Fig.  13,  and  as  specified  on  p.  23. 

The  guard  rails  should  be  of  6"  X  6"  pine,  connected  as  speci- 
fied in  the  same  place. 

To  proportion  the  joists,  first  assume  their  number  per  panel 
and  their  dimensions,  in  order  to  determine  the  total  weio-ht  of 
lumber  per  panel ;  to  this  add  the  total  maximum  panc5  live 
load,  or  the  product  of  the  panel  length  by  the  clear  roadway 
by  the  live  load  per  square  foot,  given  on  p.  5,  the  sum  being 
expres.sed    in    tons;    then,  referring   to   Table  XIII.  or  Table 
XIV.,  find,  with  the  given  panel  length  and  the  assumed  depth 
ol  joists,  the  safe  load  for  a  joist  one  inch  wide,  and  dh-ide  this 
number  into  the  total  load  just  found  :  the  quotient  will  be  the 
total  width  of  joists  per  panel,  when  laid  side  by  side.     Divide 
this  total  width  by  the  assumed  width  of  one  joist :  the  quotient 
\vill  be  the  number  of  joists  per  panel.     If  it  agree  approxi- 
mately with  the  number  assumed,  and  if  the  distance  between 
centres  of  joists,  when  in  place,  will  be  between  eighteen  and 
tucnty-four  inches,  all  right ;  if  not,  another  trial  must  be  mr.de, 
with  a  different  depth  of  joist,  and  a  new  assumed  panel  wei-^ht 
;'l  lumlKM-.     It  may  be  well,  in  any  case,  to  try  two  depths" of 
joists,   m   order  to  see   which   is   the  more  economical.     The 


68 


oj^n/.y.iKV  fKOx  inc.invAv-nRinr.Es. 


minimum  size  of  pine  joists  slioulil  be  3"  X  10":  the  maximum 
size  tliat  it  is  advisable  to  figure  on  is  4"  X  14".  because  deeper 
joists  cannot  always  be  readily  purchased.  It  is  to  be  remem- 
bered that  pine  lumber  can  be  found  in  the  market  in  only 
certain  sizes,  usually  even  inches  in  depth,  and  ahvays  even  feet 
in  len-th  ;  i.e.,  timbers  3"  X  8",  3"  X  10",  or  3"  X  12"  are  readily 
procured,  while  timbers  3"  X  9"  ^"-  3"  X  n"  are  not;  also,  if 
one  require  joists  eiKhteen  feet  six  inches  long,  it  will  be  neces- 
sary for  him  to  buy  lengths  of  twenty  feet,  and  cut  off  a  foot 
and  a  half.  Timbers  over  eighteen  feet  in  length  cost  more 
per  thousand  than  those  of  that  and  shorter  lengths. 

Tables  XV.,  XVI.,  XVII.,  and  XVIII.  give  not  only  the  sizes 
of  joists,  and  number  per  panel,  but  also  the  total  number  of 
feet,  board  measure,  of  pine  and  oak  per  panel,  including,  when- 
ever there  is  any,  waste  material. 

The  total  load  for  a  floor  beam  consists  of  the  live  load,  the 
weight  of  lumber  which  it  supports,  and  the  weight  of  the  beam 
itsctf.  The  latter  must  of  course  be  assumed  :  this  can  always 
be  done  with  sufficient  exactness  to  determine  the  floor-beam 
load.  The  latter  is  assumed  to  be  uniformly  distributed  be- 
tween centres  of  bearings. 

In  calculating  the  dimensions  of  a  floor  beam  to  sustain  a 
given  load,  the  section  of  the  web  is  to  be  assumed  ;  and  the 
beam  is  to  be  proportioned  accortling  to  the  formula  given  on 
p.  19,  and  to  the  principles  there  enunciated.  It  may  be  neces- 
sary to  make  two  or  three  designs,  in  order  to  determine  the 
most  economic  depth  ;  but  it  will  be  often  found  that  a  variation 
of  several  inches   in  the  depth  will  not   affect  the  weight   per 

foot. 

The  lower  lateral  strut,  which  is  to  be  well  bolted  to  the  floor 
beam,  will  add  consi.lerably  to  the  strength  and  stiffness  of  the 
latter.  The  joists  .should  be  dapped  on  to  the  strut  at  then- 
bearings,  so  as  to  offer  a  resistance  to  the  lateral  deflection  of 

both  strut  and  beam. 

The  lower  flange  plate,  if  there  be  one,  need  not  extend  over 
more  than  the  middle  half  of  the  length  of  the  beam.  The 
rivets  attaching  the  plate  to  the  lower  flange  angles  should  be 
staggered,  and  .should  be  spaced  ah«»«!t  four  inches  apart  ;  ami 


(>h'/)/X.l/n-  /A'OX  niGIIU-AY-liRii)GES. 


69 


the  areas  lost  from  the  plate  and  angles  by  these  rivet  holes 
should  be  deducted  when  figuring  the  net  section. 

In  heavy  beams,  several  plates  arc  often  used  to  vary  the 
section  gradually  from  the  centre  of  the  beam  to  the  ends ;  but 
if  one  share  Weyrauch's  views  upon  rivet  stresses,  as  expressed 
in  his  "Structures  of  Iron  and  Steel,"  he  will  avoid  any  such 
practice. 

Many  bridge  companies  reduce  the  depth  of  built  beams  at 
the  ends,  in  order  to  save  a  little  weight  of  iron.  This  method 
may  be  advantageous  to  the  company  which  pays  for  finished 
britlges  by  the  pound  ;  but  it  is  seldom  so  to  the  manufacturer, 
for  the  triangular  pieces  cut  from  the  web  are  often  wasted  :  be- 
sides, the  e.xtru  work  in  cutting  the  web,  bending  the  angles,  and 
making  square  rests  for  the  beam-hanger  nuts  on  the  inclined 
flanges,  more  than  counterbalances  any  saving  of  material. 

For  a  bridge  with  sidewalks,  reducing  the  depth  of  the  floor 
beams  at  the  ends  adds  to  the  appearance  of  the  structure,  and 
need  not  interfere  with  the  bearing  of  the  hanger  nuts. 

Tables  XIX.,  XX.,  and  XXI.  give  the  sizes  of  floor  beams 
for  all  cases  ordinarily  met  with. 

To  illustrate  the  method  of  proportioning  an  ordinary  floor 
beam,  let  us  take  the  case  of  a  beam  for  a  twenty-foot  panel, 
fourteen  feet  clear  roadway,  and  fifteen  feet  between  centres  of 
trusses,  the  bridge  belonging  to  Class  A. 

The  live  load  on  the  beam  will  be 

14  X  20  X  i§^^  =  14  tons. 

The  weight  of  ,  he  lumber,  from  Table  XV.,  is 
2085  X  2.5 


2000 


=  2.606  tons. 


Let  us  assume  the  weight  per  foot  of  the  beam  to  be  fifty-five 
pounds,  the  total  weight  of  same  will  then  be 


2000 


=  0.44  ton. 


The  total  load  on  the  beam  is,  therefore, 

14.000  +  -.606  +  0.440  =  I  7.046  tons. 


■JO 


O/WIXA/^ V   /A'OX   II H IIIW.W --nRllh .KS. 


The  most  economic  depth  for  the  beam  can  be  found  by  trial,  or 
by  consulting  Table  XIX.,  which  gives  J"  X  27"  for  the  section 

of  the  web.  ■       1       u 

Let  us  assume  these  dimensions,  and  take  the  eflcctive  deith 
D  equal  to  26";  then  substituting  in  the  formula  given  on  p.  ig, 
omitting  A\  and  remembering  that  7'  =  4  tons  for  bridges  of 
this  class,  gives 

the  half  of  which  is  1.28  d",  corresponding  to  a  wei-ht  per  foot 
of  4.27  pounds,  because  a  bar  of  wrought-iron  one  inch  square 
and  three  feet  long  weighs  just  ten  pounds.  Referring  to  Car- 
negie's "  Pocket-Companion,"  p.  68,  we  find  that  a  2.^' X  3"  44* 
angle  will  be  required.  Let  us  see  if  a  2"X3"  5*  '-mj^'*-^  ^^;'ll 
dol^or  the  bottom  flange.  Assuming  that  the  rivets  are  |", 
and  the  holes  \};\  in  diameter,  the  area  lost  by  a  rivet  hole  will 
be  2  X  *■'-"  X  11"  =  0.430",  which,  added  to  2.56,  gives  2.99  c", 
corresponding' to  two  angles,  each  weighing  five  pounds  per 
foot  The  assumed  angles  will  therefore  be  exactly  what  are 
required.  For  stiffeners,  let  us  use  2"X2"  3-1*  -ingl^'S-  I'our 
of  them  at  each  end  of  the  beam  will  be  needed  to  take  up  the 
compression  produced  by  the  stress  in  the  beam  hangers,  leaving 
a  space  between  the  inner  angles  equal  to  about  fourteen  feet. 

The  ratio  of  thickness  of  web  10  depth  of  same  is  -^^^  —  \q^ 

Referring  to  p.  19,  we  find,  by  interpolating,  that  the  distance 
between  "stiffeners  should  be  1.65  times  the  depth,  or  about 
44.1".  The  number  of  spaces  between  stiffeners  in  the  four- 
teen feet  will  be  -^^^i^  =  4,  requiring  six  stiffeners,  three  on 
each  side  of  the  web.  The  filling  plates  will  have  to  be 
_5_"  X  2"  X  22.1". 

^^The  method' of  finding  the  number  and  distribution  of  the 
rivets  in  the  flanges  will  be  treated  in  Chapter  XIII.:  for 
the  present,  it  will  be  sufiiciently  accurate  to  assume  that  the 
average  spacing  is  two  inches  and  a  half. 


tVv7V.\./A'J-   JA\).\    ///(/// If.  I  i-ZlAV/JuJ'S. 


71 


uctivc  ck'i  th 
ven  on  p.  19, 
r  bridges  of 


icrs,  three  on 
1    have    to    he 


Wo  arc  now  ready  to  pass  to  the  hill  of  iron   for  the  hcani, 
the  list  of  details  for  which  is  ^iveii  on  p.  30. 


nil. I,  or  ii<()\.« 


Wcl) 

I 

i" 

27" 

16' 

3O0# 

r|)per  flan    •        .     . 

2 

2i"X3" 

4.4#L 

16' 

141  " 

Lower  Han^c    .     .     . 

2 

2"X3" 

S*L 

16' 

iro" 

Still' ning  angles.     . 

14 

2"X2" 

3.i*L 

26i" 

f/. " 

Filling  plates  .     .     . 

'  1 

6  " 
ID 

2" 

22i" 

5S-' 

Rivet  heads     .     .     . 

220 

pairs 

(h) 

o.i6# 

35" 

Tofal  weight  of  beam  . 

847* 

Dividin-,-  847  by  16  gives  53  pounds  as  the  weight  per  foot  of 
the  tlixir  beam. 

Referring  to  Table  XIX..  wc  find  that  the  beam  there  given 
agrees  with  the  one  just  designed  in  e\ery  respect,  except  that 
the  weight  is  a  pound  and  a  half  per  foot  greater.  This  is 
owing  to  the  fact  that  the  weights  in  the  tables  of  floor  beams 
were    made    large   enough   lo  cover  a   slight   variat 


ion   in  the 


d 


esignnig. 


There  is  no  need  for  proportioning  rolled  beams,  be 


cause  m 


Carnegie's  "  I'ocket-Companion,"  pp.  33-44,  are  given  the  work- 


ms. 
I'll 


,^-loads  for  all   the    I 


)eams   rolled   at   the    Union    Iron    Mills. 


ese  loads  are  directly  applicable  to  bridges  of  Classes  B  and 

multiply  the  calculated  load  upon 


C.     For  bridges  of  Class  A, 

the  required  beam  by  six  (6),  and  divide  by  five  (5),  the 


n  searcl 


in  the  "Companion  "  for  a  beam  to  sustain  th 


e  resulting  lf)ad. 


Plate  girders  for  short  spans  are  to  l)e  designed  according  to 
exactly  the  same  principles  as  those  laid  down  for  the  designing 
of  floor  beams.     The  details,  t 
there  should  be  two  inclined  stiff 


00, 


the  beam,  one  on  each  side  of  the  web,  their  low 

over  the  edge  of  the  bed  plate  nearest  to  the  centre  of  th 


are   the  same,  except   that 

ening  angles  at  each   end  of 

er  ends  resting 


e  s 


IS  shown  111 


ate 


pan, 


Th 


17- 


e  distance  apart  of  plate  girders   should  not   exceed  four- 


*  Tlie  metliod  for  preparing  this  table  K  explaineil  in  Chapter  XIV. 


Xf'^ 


..^.  ^ 


n-. 


^.J^  ^ 


IMAGE  EVALUATION 
TEST  TARGET  (MT-3) 


1.0     Hfi 


I.I 


1.25 


2.8 


1^ 

•is   loK 

UUI- 


||||2.? 

1.8 


1.4    ill  1.6 


p% 


(? 


.% 


7i 


7: 


/^ 


Photographic 

Sciences 
Corporation 


23  WEST  MAIN  STREET 

WEBSTER,  N.Y,  14580 

(716)  872-4503 


IN- 


ORDINARY IRON  II IG I nv AY-BRIDGES. 


liiii 


teen  (14)  feet,  on  account  of  the  difificulty  in  obtaining  joists 
lar<;c  enough  to  support  the  concentrated  wagon-loads. 

Trussed  beams  are  sometimes  made  with  one  trussing-post, 
and  sometimes  with  two.     To  determine  the  relative  length  of 
the  part  between  the  posts  in  the  latter  case,  — 
Let 

/j  =  length  of  an  end  division, 
/j  =  length  of  the  central  division, 

and 

/=  2  /j-f-  A  =  length  of  beam  between  centres  of  supports. 

The  whole  beam  is  now  divided  into  three  beams,  two  of  which 
may  be  considered  fixed  at  one  end,  and  supported  at  the  other, 
and  the  third  fixed  at  both  ends.  If  the  moments  of  the  loads 
do  not  balance  each  other  over  the  posts,  the  rigidity  of  the 
connection  there  may  be  considered  sufficient  to  insure  fixed- 
ness. 

The  greatest  moment  for  a  beam  fixed  at  one  end,  supported 
at  the  other,  and  subjected  to  a  uniform  load  of  w  tons  per 

lineal  foot,  is 

\T.i'l{'  at  the  fixed  end. 

The  greatest  moment  for  a  beam  fixed  at  both  ends  is 

■^u>l.£  at  either  end. 

Remembering  the  assumption  of  the  fixedness  of  the  beam  over 
the  posts,  it  is  evident,  that,  in  order  to  make  the  moments 
over  these  points  a  minimum,  the  two  values  found  should  be 
made  equal  to  each  other,  so  that 


or 

and 

Again : 
therefore 
and 


11  _  3/2 

2    —  '2  1  ' 


/,  =  1.224/j. 
/=  2/,  -f  A=  3.224/1: 

/,  =  0.31/, 
=  /(l    -   2    X   0.31)  =0.38/, 


ussing-post, 


ORDINARY  IRON  HIGHWAY-BRIDGES.  73 

,)r  the  length  of  the  central  portion  should  be  about  four-tenths 
of  that  of  the  beam  between  .suj)porls. 

To  proportion  the  upper  flange  of  a  trussed  beam  having  two 
trussing-posts,  such  as  shown  in  Plate  II.,  Fig.  16,  — 

Let 

d  =  depth  of  beam  proper, 
D  -  depth  between  centre  line  of  beam  proper  and  centre  line  of 

bottom  cnord  of  trussing, 
7i<  =  uniform  load  per  foot  on  beam, 
/■=  },7c{/^  +  I,)  =  load  concentrated  over  one  post, 
and  let 

/,  /i,  and  4  have  the  same  values  as  before. 

The  area  of  the  compression  flange  of  the  beam  necessary  to 
resist  bendmg  only  is  given  by  the  formula 

where  C  is  the  intensity  of  working-stress  upon  the  flange  to 
be  taken  from  the  "General  Specifications,"  p.  13,  and  A'  is 
the  area  of  the  web. 
The  stress  in  either  chord  of  the  truss  is 

D' 

Let  /f  equal  the  area  of  one  flange  of  the  beam,  supposing 
that  the  loads  P  were  really  concentrated  over  the  posts,  instead 
of  bemg  distributed,  then 


and 


A'  +  2^"  =  area  of  ideal  beam, 

C\A'+2A")  =  F=^^^; 
D 


where  C  is  the  intensity  of  working  resistance  to  compression. 


*  For  proof  of  tins  formul.-,,  see  .Apper.dix  U,  which  gives  the  demonstration  fo 


r  a  similar 


ili 


}i\ 


\f 


74 


OKDIN/IRV  IRON  HIGHWAY-BRIDGES. 


It  should  be  about  three  (3)  tons  for  bridges  of  Class  A,  and 
four  (4)  tons  for  those  of  Classes  B  and  C.  The  total  area  of 
the  lower  flange  of  the  beam  should  therefore  be 


If  the  beam  be  a  rolled  one,  as  it  nearly  always  is,  there  is  no 
need  of  figuring  upon  the  size  of  the  upper  flange  ;  while,  if  it 
were  a  built  beam,  it  might  be  as  well,  for  practical  reasons,  to 
make  the  flanges  of  the  same  size,  although  theoretically  a 
slight  reduction  in  the  area  of  the  upper  one  would  be  per- 
missible. 

For  a  beam  with  a  single  trussing  post,  the  bending-moment 
over  the  post  is 

and  the  area  of  flange  necessary  to  resist  bending  is,  as  before. 


A  = 


_  lii/i^ 


St/C 


1//' 


P,  in  this  case,  is  equal  to  zc/^ ;  making  the  re-action  at  each  end 
of  the  beam,  under  the  supposition  of  concentrated  loading, 

The  direct  compression  on  the  upper  chord  of  the  trussed  beam 
is,  therefore, 


r-^^=C'{A'+2A"): 


and  the  total  area  of  the  flange  is 


^'L,c"fl  +  ,c,o-K. 


'lii 


OIWINARY  IIWNHIGHWA  Y-B RIDGES. 


75 


ing-moment 


russed  beam 


The  author  does  not  claim  that  these  formulas  are  exact ;  but 
practically  they  will  prove  to  be  a  great  deal  more  useful  than 
others  theoretically  more  correct,  but  also  much  more  complex. 

At  the  end  of  Chapter  XIII.,  there  is  given  a  complete  design 
for  a  trussed  floor  beam  with  two  posts.  The  reason  why  it  is 
not  inserted  here  i.s,  that  it  is  necessary  to  understand  the 
contents  of  Chapters  X.-XIII.  inclusive,  in  order  to  properly 
proportion  the  details. 

The  weight  supported  by  the  four  hangers  that  usually  sus 
tain  a  beam  is  that  of  a  panel  live  load  upon  both  trusses,  that 
of  the  lumber  in  one  panel,  and  that  of  the  beam  itself.    The 
total  load  divided  by  eight  times  the  intensity  of  working-stress 
will  give  the  area  of  the  section  of  a  hanger. 

Square  sections  lie  more  closely  to  the  pins  than  round  ones, 
and  take  up  less  room  in  the  packing ;  but  they  must  always  be 
upset,  which,  in  short  hangers,  makes  them  more  expensive  than 
round  ones. 

Single  beam  hangers  are  allowable  in  skew  bridges,  where, 
indeed,  their  use  is  often  unavoidable,  or  in  narrow  bridges 
with  short  panels,  where  there  is  not  much  weight  to  be  sup- 
ported. 

Tables  XXII.,  XXIII.,  and  XXIV.  give  the  sizes  of  beam 
hangers  for  nearly  all  bridges  without  sidewalks. 

The  most  simple  manner  of  finding  the  size  of  single  beam 
hangers  for  any  roadway  and  panel  length  is  to  look  in'the  table 
of  hip  verticals  of  the  same  class  for  the  section  required,  and 
multiply  it  by  one-half  of  the  ratio  of  working-stresses  for  hip 
verticals  and  beam  hangers:  the  result  will  be  the  area  in 
square  inches  of  the  section  of  the  hanger. 

If  the  floor  and  joists  be  of  oak,  the  tables  of  floor  beams  and 
beam  hangers  can  still  be  employed  by  supposing  an  increase 
of  one  foot  in  the  panel  length. 


!:   f 


76 


0/WIA'ARV  IROiV  HIGHWAY-r>Rllh.l-:s. 


CHAPTER  X. 


THEORY   OF   PIN    PROPORTIONING. 


if    8 


The  subject  of  "bridge  pins"  is  one  deserving  of  more  con- 
sideration than  has  been  accorded  it  by  engineers,  and  authors 
of  technical  works.  Until  1873,  when  Mr.  Charles  Bender,  C.E., 
presented  his  paper  on  "  Proportions  of  Pins  used  in  Bridges  "  to 
the  Amei'ican  Society  of  Civil  luigineers,  very  little  was  known 
concerning  it ;  the  usual  custom  among  engineers  when  propor- 
tioning pins  having  been  to  allow  one  square  inch  of  pin  area 
for  every  eight  or  ten  thousand  pounds  of  shear  in  the  section 
most  subject  to  shearing-stress.  As  ]\Ir.  Bender  states  gener- 
ally, and  as  will  be  shown  farther  on  to  be  true  for  iron  bridges, 
it  is  not  the  shear,  but  the  bending-moment,  which  causes  the 
greatest  tendency  to  rupture  ;  so  that  in  any  iron  structure  it 
will  be  sufficient,  in  finding  the  sizes  of  pins,  to  calculate  the 
greatest  moment  induced  in  them  by  the  various  members 
coupled  thereon,  and  to  proportion  accordingly,  due  regard 
being  paid  to  the  stresses  in  the  eye-bar  heads.  Before  making 
any  investigations,  it  will  be  well  to  review  and  summarize  the 
most  important  results  of  the  investigations  of  others  in  this 
subject. 

The  principal  conclusions  arrived  at  by  Mr.  Bender  are,  that, 
for  a  well-fitting  pin  of  large  diameter,  a  pressure  on  the  bearing- 
surface  of  six  tons  per  square  inch  is  not  too  large ;  that  for 
simplicity  it  is  well  to  assume  that  this  pressure  is  uniformly 
distributed  over  the  diameter  of  the  pin  ;  that  wrought-iron, 
after  millions  of  impacts,  may  break  on  the  side  where  the 
stress  is  tensile,  but  never  on  the  side  where  it  is  compressive, 
the  ultimate  resistance  to  crushing  being  about  thirty  tons  per 
square  inch  ;  that  the  shearing-stress  at  the  centre  of  a  pin  is 


ORD/X.i/n-  //WX  IIICllWA  y-URIDCES. 


/  / 


one  and  thrcc-cij^hths  times  the  average  shear  on  the  whole 
section  ;  that  in  iron  and  steel  the  ratio  between  the  greatest 
allowable  tensile  and  the  -reatest  allowable  shearing-stresses 
should  be  as  5  to  4,  which  would  make  the  uniformly  dfstributed 
shear  2.91  tons  per  square  inch,  to  correspond  with  a  tensile 
stress  of  5  tons  per  square  inch  ;  and  that,  owing  to  various  con- 
siderations, iron  in  ]Mns  may  be  strained  much  more  than  similar 
iron  in  tension  members. 

Mr.  K  Baker,  C.K.,  in  "  Beams,  Columns,  and  Arches,"  treats 
of  pins  merely  incidentally.  He  finds,  that,  for  iron  in  solid 
circular  beams,  the  average  value  of  <^  is  11/  where  /  is  the 
ultimate  resistance  per  square  inch  to  rupture  by  tension,  and 
c/.  the  difference  between  the  apparent  ultimate  resistance  per 
square  inch  to  rupture  by  bending  and  /,  according  to  the  equa- 
tion /''=/+ qi,  /'"being  the  apparent  ultimate  resistance  per 
.square  inch  of  the  extreme  fibre  which  first  gives  way  ;  and, 
that  for  steel,  the  value  of  <^  varies  between  1.7/  and  1.9/ 

Professor  Burr  devotes  five  pages  of  his  work  on  "  Stresses  in 
]5ri(lge  and  Roof  Trusses  "  to  the  subject  of  pins,  and  illustrates 
the  particular  case  of  a  suspension-bridge  cable  pin,  and  a  gen- 
cral  case  for  ordinary  truss-bridge  pins. 

Professor  Du  Bois,  in  "Strains  in  Framed  Structures,"  also 
gives  a  mathematical  discussion  of  how  to  find  the  maximum 
bcndingmoment. 

Table  XII.  gives  the  working  bending-moments  on  all  the 
non  and  steel  pins,  and  the  working-shear  on  all  the  steel  pins, 
which  will  ever  be  required  for  highway-bridges.  Having  cal- 
culated the  bending-moment,  the  requisite  diameter  for  the  pin 
can  he  found  by  looking  down  the  column  for  the  class  of  bridge 
considered,  until  a  bending-moment  at  least  equal  to  the  one 
found  is  reached.  The  diameter  will  be  found  at  either  end  of 
the  horizontal  row  thus  located.  The  use  of  the  columns  for 
shear  will  be  made  apparent  presently. 

The  upper  and  lower  horizontal  lines  in  the  tables  of  bearino-s 
(lables  XXVT.  and  XXVII.)  give  the  diameters  of  the  pins; 
the  extreme  vertical  lines,  the  necessarv  widths  of  bearing-sur- 
tacT  at  each  end  of  the  pins,  including  both  channel  and  re- 
t'lilorcing  plates  ;  and  the  other  vertical  lines,  the  permissible 


11'^ 


78 


ORDINARY  IRON  IIIGHVVAY-BRIDGES. 


pressure,  on  the  bearings.  The  method  of  using  these  tables  is 
the  following.  The  pressure  .vhich  the  pin  is  to  carry  is  to  be 
taken  from  the  diagram  of  stresses.  A  trial  diameter  is  then 
assumed.  The  vertical  column  in  either  Table  XXVI.  or  Table 
XXVn.,  headed  by  this  diameter,  is  to  be  followed  down,  until 
a  number  nearest  the  pressure  to  be  carried  is  found.  At  either 
end  of  the  horizontal  row  thus  located  will  be  found  the  proper 
width  of  bearing.  Knowing  the  width  of  bearing,  diameter  and 
pressure,  the  moment  to  which  the  pin  is  subjected  may  be  at 
once  calculated.  Turn,  then,  to  Table  XII  ,  and  see  if  this 
moment  agree  with  the  working-moment  corresponding  to  the 
trial  diameter.  If  it  does,  all  right :  if  not,  another  trial  is  to  be 
made,  with  a  new  assumed  diameter.  After  a  little  experience, 
the  first  trial  will  be  sufficient.  A  consideration  of  other  de- 
tails, such  as  widths  and  depths  of  eye  bars,  etc.,  will  frequently 
aid  very  much  in  these  trials. 

To  find  the  least  value  of  the  ratio  of  the  diameter  of  pin  to 
depth  of  eye  bar  in  an  'ron  bridge,  by  considering  the  tension 
in  the  bar,  and  the  pressure  between  the  pin  and  bar,  — 
Let 

w  —  width  of  bar, 

fl'j  =  depth  of  bar, 

d  —  diameter  of  pin, 

C  =  intensity  of  working  compressive  stress, 

T  =  intensity  of  working  tensile  stress ; 


then 
and 


wd^T  =  tension  in  bar, 
wdC  =  compression  on  pin  and  eye. 


These,  of  course,  are  equal  ;  and,  as  C  =  6tons  when  T: 
tons,  there  results  the  equation, 

d=y,  =  0.833//,, 


.1! 

i  3! 


which  shows  that  the  diameter  of  the  pin  should  never  be  less 
than  eighty-three  per  cent  of  the  depth  of  the  bar.  It  is  possi- 
ble, though,  that  good  iron  of  twenty-five  tons  tensile  strength 
will  resist  more  than  thirty  tons  per  square  inch  in  comprcs- 


ORDINARY  IRON  HIGmVAY-liRlDGES. 


79 


sion  :  consequently  d  may  be  taken  at  o.M^  as  a  matter  of  con- 
venience. 

To  find  the  proportion  between  width  and  depth  of  bars  for 
the  smallest  allowable  pin  in  an  iron  bridge,  — 

Let  the  notation  be  as  before,  and  first  let  us  suppose  that 
there  be  but  one  pair  of  bars  acting  at  each  end  of  the  pin,  and 
that  the  total  tension  be  a  fixed  quantity.  The  stress  in  one  bar 
is  iiY/,7',  and  its  moment  is  wV,7:  This  must  be  equal  to  the 
resisting-moment  of  the  pin,  which  is  given  by  the  well-known 
equation 


d 


Here  R  —  \T,    /  =  \-,:r\    and  D  =  r  =  -,  substituting  which 


gives 


Equating  the  two  values  of  the  moments  gives 

w'd,T  =  -^nrd\ 


or 


64    d. 


Now,  to  make  the  diameter  of  the  pin  as  small  as  possible, 
the  moment  of  the  stress  must  be  made  as  small  as  possi- 
ble ;  and,  as  the  stress  is  constant,  the  lever-arm  w  must  be 
made  as  small  as  possible.  But  the  product  of  rv  and  d^  is  a 
constant :  so  when  zv  is  smallest,  d^  must  be  greatest.  But  the 
greatest  value  of  d^  is  {d ;  substituting  which  gives 


2      3"' 


64 


and 


64       125 


«'i'  =  o.754«',«, 


or  about  one-fourth  of  the  depth  of  the  bars. 

If  there  be  two  pairs  of  similar  bars  acting  at  each  end  of  the 
pin,  instead  of  one  pair,  the  equation  of  moments  will  be 


2W%T  =  -^\nTd», 


8o 


o/c/)/.v.i/n-  /A'o.v  nir.iiwA  Y-HRiihiEs. 


or 


w  = 


As  before,  to  make  d  a  minimum,  re  must  be  made  a  minimum, 
or  ,/,  a  maximum  :  therefore  d  =  \il^,  which,  substituted,  gives 

7t'  =  0.194^/p 

or  about  one-fifth  of  the  depth  of  the  l)ars. 

For  three  pairs  of  simihir  bars  at  each  end  of  the  pin,  the 
equation  of  moments  will  be 

substituting  in  which  \d^  for  r/ gives 

7.'  =  o.i5(y„ 

or  about  one-sixth  of  the  depth  of  the  bars. 

Finally,  if  there  be  four  pairs  of  similar  bars  at  each  end  of 
the  pin,  the  equation  of  moments  will  be 


which  gives 


6,w"d^T  =  i\TTd\ 


a'  =  o.i37./i, 


or  about  one-seventh  of  the  depth  of  the  bars. 

To  find  the  greatest  working  shearing-stress  (supposed  to  be 
uniformly  distributed)  in  terms  of  the  working  resistance  to 
tension,  — 

Let  5  =  actual  varying  resistance  to  shearing,  considered 
uniforml}'  distributed.  The  greatest  value  of  .V  will  correspond 
to  a  value  of  w  equal  to  0.274^/,;  for  suppose  the  moment  to 
remain  at  its  maximum  value,  and  the  dimensions  of  the  bar 
to  vary  (consequently  the  stress  therein  also),  the  tension  in 
the  bar  will  be  greatest  for  the  value  of  ti'  corresponding  with 
the  greatest  value  of  d^ :  therefore  the  shear  will  also  be  great- 
est for  that  value. 

Equating  the  tension  to  the  shear  gives 


:  i! 


^  minimum, 


ach  end  of 


Substituting  yiov  ,/,,  and  o.274^«,/)  for  w,  gives 


81 


and 


0-274  (5'/)  ^7'  = 
^^=  0545  7',- 


l"l"    'f=S     tons,    .S"='>7->i;    folic         IJ,.f    ^u 

V.I..0  for  .V  is,  acconli,,':, .;.,,'"    ';:;r'"L^""™'"'= 

;'-•  ■'  -.V":;;  i-"  ^e  p™,,..,,  „,..,„;„;,?,:';, .  ,hi:;":;:i 

l""li".^'.  .t  w,ll  1,0  str„„K  o,„„,g|,  ,„  resist  shear   ami    n"  f^ 
■I-.  I"f...c  .1.0  pin  co.„„  shear,  it  >v.„„„  eiU.er  brei^^    bl  b       ' 

11.^  "r  en,sh„,K,  "r  the  eye  of  the  Ixir  w.nil.l  „ivc  wiv     A  si,  ^M 
.,u-es.,,ation    f„r  steel   bridges,  where  7' =  i  3/    ,  „,    C-    'r 
.....I  A'  (.he  intensity  „f  working  bentii„,.s,re;,  =     S^T,  e,' 
./=o.S7]4,/„  t,.  =  o.i.s,f;,/    and  .V-soj-  tn,,s       1    ^      . 
"'">■  "'  »-^'^'n„,s.ress'w„en  tb-.^ntstr^.e:  ^  ,:';,?' 

l.-lin«-hn,it,  and  the  ratio  ;;  for  ,ha,  e„„,h,i„n  of  stress  is  a. 
..s  i.uninunn,  an<l  eonsetpiently  the  area  of  the  bar,  the  tension 
.heren,,  an,   the  shear  „n  the  ,,in,  at  their  maxin  a       I  .       h 
.reae.,  allowable  shear  is,  aecor.lin,  ,0   llentl      "  X    -   X  7' 

">,  on  a  steel  pn,  n,  opposite  direetions.  or  a  sin.^ie  steel  bar 
a.:uns    a  steel  bearing,  the  pin  in  certain  eases  wi  1    e  ,h, I 

:::::u:::Ltr::?is:-' ""  •"-'"-  ■--  - '-  ^■'"' 

channels   can  be  found   after  uli.v-i,  h  '-"-cwccn  post 

tars  in  the  bridge  ^^'i:^^:^:^ ^^^^Vl^'  '"^ 

-  -npletl  on  the  same  pin  pnll  i„  ,he  sante  direct!  nunes 


1^* 


82 


()AW>/.\.l/n     /A'<>.\     ///</////./  J -A'AV/^i/A'.V. 


as  to  reduce  the  hen(lin<;momcnt.s  ;  and  that  the  dia-jjonal  ties 
be  placed  close  to  the  posts,  and  the  beam  han^^ers  close  to 
the  ties.  ICspecial  care  is  needed  at  the  panel  point  where  the 
number  of  chord  bars  is  different  in  the  consecutive  panels.  It 
is  possible  to  arranj^e  the  bars  there,  so  that  there  wilt  be  an 
extremely  large  moment  produced,  or  so  that  it  will  be  smaller 
than  at  any  other  panel  point  of  the  bottom  chonl.  The  ne<;lect 
of  any  of  these  precautions  will  cause  an  undue  bending-moment 

on  the  pin. 

The  arrangement  completed,  the  next  questions  to  be  decided 
are,  first,  under  what  condition  of  loading  will  each  pin  take 
its  greatest  bending  moment,  and,  second,  at  what  point  on 
the  pin  will  this  be  found.  In  large  bridges,  and  in  many  well- 
proportioned  small  ones,  the  bottom  chord  pins  are  subjected  to 
their  greatest  bending-moments  when  the  bridge  is  fully  loaded. 
Under  this  condition,  the  stresses  in  the  chord  bars  can  be  taken 
from  the  diagram  of  stres.ses;  but  those  in  the  main  diagonals 
must  be  calculated  for  the  load  covering  the  whole  bridge,  and 
their  horizontal  and  vertical  components  be  ascertained. 

After  having  hail  some  practice,  one  will  very  often  be  able 
by  simple  inspection  to  decide  at  what  place  the  greatest 
moment  of  flexure  will  exist ;  but,  if  not,  it  will  be  necessary 
to  calculate  the  values  of  both  horizontal  and  vertical  momenls 
at  different  i)oints,  and  find  where  their  combined  result  is  a 
maximum.  As  Professor  Burr  shows,  the  actual  moment  is 
represented  by  the  diagonal  of  a  rectangle  whose  sides  repre- 
sent the  vertical  and  horizontal  moments.  It  is  usually  more 
convenient  to  square  the  component  moments,  aild  the  results, 
and  extract  the  square  root  of  the  sum,  than  to  make  out  a 
diagram. 

The  moments  of  the  stresses  can  be  easily  recorded  by  draw- 
ing two  curved  lines,  as  shown  in  the  accompanying  diagram, 
representing  the  directions  in  which  tlu' 
stresses  tend  to  bend  the  pin,  and  writing 
each  moment  as  calculated  under  one  or 
other  of  them,  according  to  whether  it  would 
|)rotluce  ])ositive  or  negative  rotation.  The 
difference  between  the  sums  of  each  column  will  give  the  actual 


:  1: 


!■' 


o/w/x.i/n-  /A'o.y  ///<;// ir.i  r-/,>A7/jf;/;',s-. 


83 


led  bv  dr:uv- 


horizonal  or  vertical  moment,  as  the  case  may  be.     The  ondi- 
ii..n  that  a  load  covering  the  whole  i)rid-e  may  not  produce  the 
-reatest  moment  in  the  bottom  ehord  pins  is  either  when  there 
is  a  sm-le  counter  coupled  at  the  centre  of  the  pin,  or  a  main 
(liaj;onal  coupled  at  a  distance  from  the  member  that  takes  up 
its  stress.     As  a  rule,  single  counters  and  single  beam  hangers 
are  to  be  avoided,  on  account  of  the  unnecessarily  large  bend- 
in-moments  they  produce.     The  size  of  pin   for  the  hip  joint 
depends  greatly  upon   the  arrangement   of   the   bars  which  it 
couples.     In  a  double-intersection  bridge,  where  there  are  two 
hip  verticals,  two  long  diagonals,  and  two  short  ones,  the  best 
arningement  is  to  put  one  pair  of  diagonals  on  the  outside  of 
the  chord,  and  the  other  pair  inside,  close  to  the  bearing;  the 
verticals  coming  next,  and  being  kept  apart  by  a  filler.     Some- 
times it  is  not  advi.sable  to  couple  outside  of  the  chord,  in  which 
case  the  moment  would  become  so  great,  that  it  would  necessi- 
tate  the  employment  of  a  pin  whose  diameter  would  make  the 
heads  of  the  eye  bars  too  large  for  the  space  allotted  them.     In 
such  a  case,  a  steel  pin  can   be  used  to  advantage.     IIinr--ed 
ends  at  the  hip  joints  require  large  pins,  for  the  entire  stresses 
in  both  chords  and  batter  braces  come  upon  them  with  great 
leverage,  due  to  the  necessarily  large    bearing-surface.     Such 
a  connection   is    not   advantageous  :    it   is   better  to  allow  the 
channels  to  abut.     Such  hinged  ends  are  a  great  convenience 
in  erection,  but  usually  necessitate  an  increase  in  the  sizes  of 
the  batter  braces  and  the   top  chords  at  the  end  panels.     A 
detail  to  obviate  this  necessity  will  be  given  in  Chapter  XIII. 

It  is  not  neces.sary  to  consider  the  bending-effect  of  the 
stresses  in  the  lateral  rods  upon  the  chord  pins,  for  the  wmd 
and  the  live  load  are  not  supposed  to  act  simultaneously. 

Lateral  rods  should  always  be  so  connected  to  the  chord  pins, 
that  the  effect  of  the  stress  in  the  outer  one  will  be  to  diminish 
the  horizontal  component  of  the  moment  on  the  pin  ;  i.e.,  if  the 
tendency  of  the  chord  and  web  stresses  is  to  bend  the  pin  con- 
vex to  the  middle  of  the  bridge,  the  outer  lateral  rod  should 
IK.int  towards  the  middle ;  but,  if  it  be  to  bend  the  pin  concave 
to  the  middle  of  the  bridge,  the  outer  lateral  rod  should  point 
towards  the  nearest  end  of  the  span. 


^1; 


84 


ORDINARY  IRON  HIGHWAY-liRinCES. 


The  ends  of  pins  have  to  be  reduced  in  diameter,  so  that  the 
nuts  and  pin  pilots  may  be  screwed  thereon.  Care  must  there- 
fore be  taken  in  proporiioning  small  pins  to  see  that  sufficient 
area  be  left  under  the  root  of  the  thread  to  resist  the  tension 
on  that  section  caused  by  the  greatest  transverse  components 
of  the  stresses  in  the  lateral  rods.  The  principal  objection  to 
the  use  of  large  pins  is  not  always  the  undue  weight  of  the 
pins  themselves,  but  the  increased  size  of  the  chord  and  tie-bar 
heads,  and  the  room  that  they  take  up. 

On  the  other  hand,  it  is  not  always  desirable  to  use  the 
smallest  possible  pin,  as  the  width  of  the  bearing  is  an  inverse 
function  of  the  diameter  of  the  pin  :  so  if,  owing  to  the  neces- 
•'ty  of  a  large  number  of  rivets,  the  re-enforcing  plates  be  long, 
.  micht  be  economical  to  increase  the  diameter  so  as  to  reduce 
.le  width.  Thickening  the  heads  of  eye  bars  has  an  injurious 
effect  on  the  pins,  although  a  beneficial  one  upon  the  heads,  for 
the  lever  arms  of  the  stresses  are  thereby  increased. 

Bridges  with  weak  pins  will  not  necessarily  fail  by  the  rup- 
ture of  the  pins.  The  reason  for  this  is  thus  stated  by  Professor 
Rurr:  "The  distortion  of  the  pin  beyond  the  elastic  limit  will 
relieve  the  outside  eye  bars  of  a  large  portion  (in  some  cases, 
perhaps  all)  of  the  stress  in  them.  This  result  will  produce 
a  redistribution  of  stress  in  the  eye  bars,  by  which  some  will 
be  understrained,  and  the  others  correspondingly  overstrained. 
Thus,  although  the  pin  may  not  wholly  fail,  the  safety  of  the 
joint  will  be  sacrificed  by  the  overstrained  metal  in  the  eye 
bars." 


ORDINARY  JROA'  HIGnWAy-BRWuES. 


Ill 


so  that  the 
must  there- 
it  sufficient 
the  tension 
components 
)hjection  to 
itrht  of  the 
I  and  tie-bar 

to  use  the 
s  an  inverse 
I  the  neces- 
.tes  be  long, 
as  to  reduce 
an  injurious 
le  heads,  for 

by  the  rup- 
by  Professor 
ic  limit  will 
some  cases, 
,vill  produce 
:h  some  will 
)verstrained. 
afety  of  the 
in  the  eye 


85 


CHAPTER  XI. 

PRACTICAL  METHOD   OF  PIN  PROPORTIONING. 

The  ordinary  method  of  pin  proportioning  is  to  figure  the 
diameters  of  a  few  principal  pins,  and  to  make  the  others  of 
the  same  sizes.  Thus,  by  inspection,  can  be  found  which  pin 
near  the  middle  of  the  bottom  chord  is  subjected  to  the  great- 
est bending-moment.  If  there  be  an  even  number  of  panels  in 
the  span,  it  will  be  the  middle  pin  ;  but,  if  there  be  an  odd 
number,  it  may  be  the  first  or  second  pin  from  the  middle, 
according  to  the  number  and  arrangement  of  the  chord  bars. 
The  vertical  component  of  the  bending-moment  on  any  one  of 
these  pins  is  so  small  in  comparison  with  the  horizontal  com- 
ponent, that  it  may  be  neglected.  For  bridges  with  an  even 
number  of  panels, — 

Let 

T  =  tension  in  middle  panels  of  lower  chord, 
and 

u>  =  the  average  thickness  of  chord  bars  in  these  panels ; 
then,  appro.ximately, 

—  =  bending-moment  on  middle  pin. 

This  formula  may  be  applied,  but  perhaps  with  less  .ccuracy, 
to  a  bridge  having  an  odd  number  of  panels  ;  and,  if  the  chord 
be  properly  packed,  the  error  will  be  upon  the  side  of  safety. 

With  the  exception  of  the  chord  pins  at  the  shoes  and  at  "the 
first  panel  points  from  the  ends  of  the  span,  all  the  lower  chord 
pms  may  have  a  diameter  corresponding  to  this  ma.vimum  bend- 
mg-moment. 


86 


ORDINARY  IRON  HIGHWAY-BRIDGES. 


To  find  the  size  of  the  lower  chord  pin  at  the  first  panel 
point,  use  the  formula, 


H  = 


Trt) 


for  the  horizontal  component  of  the  moment,  and  the  formula 


for  the  vertical  component ;  t  being  the  intensity  of  working- 
stress  for  the  hip  verticals,  A  their  area  (S.  R.),  to  be  taken 
from  one  of  Tables  VI.,  VII.,  and  VIII,  <•/ the  diameter  or  thick- 
ness of  a  hip  vertical,  and  d'  that  of  a  beam  hanger. 
The  moment  given  by  the  formula 


applied  to  Table  XII.  will  determine  the  diameter  required. 
This  diameter  is  to  be  used  also  for  the  pin  at  the  shoe. 

To  find  the  size  of  a  hip  pin,  lay  off  the  stresses  in  one  hip 
vertical  and  one  end  main  diagonal  to  any  convenient  scale,  and 
find  the  value  of  their  resultant  by  the  parallelogram  of  forces. 
This  resultant  will  determine  the  thickness  of  the  bearing,  a 
trial  diameter  being  first  assumed.  It  is  possible  that  this  bear- 
ing will  have  to  be  increased,  so  that  there  will  be  enough  iron 
to  transfer  the  stresses  from  the  batter  brace,  hip  verticals,  and 
diagonals  to  the  chord,  as  will  be  explained  in  Chapter  XIII. 
An  appro.ximate  test  of  the  sufficiency  of  the  bearing  in  this 
respect  may  be  obtained  as  follows  :  — 

Let 

A  —  the  area  of  the  section  of  the  end  panel  of  the  top  chord, 
t/  =  depth  of  cliord  channels, 
/  =  thickness  of  web  of  an  entl  cliord  channel ; 

then  the  bearing  should  not  be  less  than  that  given  by  the 
formula 

2(1 

Ne.xt  find  the  distance  /  between  the  centre  of  the  bearing  of 


ORDIXARY  IROX  HIGHWAY- lU^IDGES. 


«7 


he  formula 


the  chord  and  that  of  the  diagonal,  also  the  distance  /'  between 
tiie  former  and  that  of  the  hip  vertical,  the  latter  being  on  the 
inside.  Calling  the  stress  in  the  hip  vertical  F,  and  that  in 
the  diagonal  5,  the  vertical  moment  will  be  /'/',  and  the  inclined 
one  .S7.  Next  lay  out  these  components  to  any  convenient  scale 
in  their  proper  directions,  and  find  their  resultant  by  the  paral- 
lelogram of  moments.  This  resultant  will  determine  the  diame- 
ter of  the  pin. 

If  the  diameter  found  agrees  with  the  one  assumed,  or  if  it 
iloes  not  agree,  provided  that  the  bearing  was  not  determined 
by  the  trial  diameter,  all  right;  but  if  the  bearing  were  so 
determined,  and  the  two  diameters  do  not  agree,  another  trial 
must  be  made. 

Where  there  are  more  than  two  main  diagonals  coupleil  at 
the  hip,  as  is  the  case  in  double-intersection  and  in  very  heavy 
single-intersection  bridges,  one  pair  is  coupled  on  the  outside 
oi  the  bearing,  and  the  other  on  the  inside  ;  so  that  theoretically 
the  greatest  bending-moment  is  equal  to  the  .stress  in  the  outer 
l)ar  multiplied  by  the  cHstahce  between  the  centre  of  the  bar 
and  the  centre  of  the  bearing.  Ihit  practically  the  moment  may 
be  greater,  for  the  distribution  of  stresses  among  the  diago- 
nals may  not  l)e  as  assumed  :  so  it  is  well  to  determine  The 
moment  by  imagining  the  outer  bar  not  to  e.xist,  and  proceeding 
as  explained  above  for  the  case  of  only  two  main  diagonals  al 
the  hip,  excepting,  of  course,  that  the  thickness  of  the  bearing 
must  be  ascertained  by  finding  the  resultant  of  the  stres.ses  in 
the  two  diagonals  and  the  hip  vertical. 

To  calculate  the  size  of  an  intermediate  upper  chord  pin,  the 
wi.Uhs  of  chord  and  post  bearings  are  to  be  determined  as  shown 
m  Chai)ler  XIII.  The  former  is  given  approximately  by  the 
last  formula,  where  A  is  the  section  of  the  panel  of  the  chord 
on  the  side  of  the  pin  towards  the  miiklle  of  the  bridge,  ami  t 
the  thicl<ness  of  the  corresponding  channel.  The  other  is  given 
I'V  the  formula 


where  A,  is  the  area  of  the  section  of  the  post,  and  h  the  depth 
of  one  of  its  channels. 


88 


o/w/y.'iA'y  /Rox  higiiwa  y-bridges. 


Next  resolve  one-half  of  the  diaj^^onal  stress  vertically  and 
horizontally  into  /'  and  /''  respectively.  Let  /  represent  the 
distance  between  the  centre  of  the  diaijonal  and  that  of  the  ex- 
tension plate,  and  /'  the  distance  between  the  former  and  that 
of  the  chord-bearing  ;  then 

V  =  PI, 


II  =  P'l', 


and 


M  -  V'//'  +  V\ 


If  the  bridge  be  a  small  one,  it  will  be  necessary  to  calculate 
only  the  size  of  the  pin  at  the  top  of  the  first  vertical  post  from 
the  end  of  the  bridge,  and  to  make  all  the  intermediate  top 


chord  pins 


of  th 


e  same  size. 


But,  if  the  bridge  be  a  large  one, 


it  will  be  better  to  calculate  the  diameter  of  the  pin  on  the  post 
midway  between  the  end  vertical  post  and  the  middle  of  tlie 
span,  and  to  make  all  the  pins  between  these  places  of  this 
diameter,  and  all  the  others  of  the  same  diameter  as  that  at  the 
eml  of  the  first  vertical  p'>st.  After  the  diameters  of  the  top 
chord  pins  are  determinetl,  the  post  and  chord  bearings  should 
be  tested  by  applying  one  of  Tables  XXVI.  and  XXVII.,  al- 
though in  most  cases  they  will  be  found  ample. 

In  double-intersection  bridges,  where  the  diagonals  are  halved, 
and  coupled  on  pins  passing  through  the  middle  of  the  pysts, 
the  size  of  any  one  of  these  pins  may  be  found  from  the 
moment 

M  =  — , 


I  • 


Ifi 


n 


where  5  is  the  stress  on  the  diagonals  as  given  on  the  diagram 
of  stresses,  and  w  the  width  of  one  of  the  main  diagonals. 

In  all  pin  proportioning  it  must  be  kept  in  mind  that  the 
diameter  of  the  pin  is  never  to  be  less  than  eight-tenths  of 
the  depth  of  the  deepest  bar  coujiled  thereon. 

The  author  wisiies  to  call  attention  to  the  superiority  (in  his 
opinion)  of  the  simple  method  given  in  this  chapter  for  propor- 
tioning lower  chord  pins  by  formula  over  the  apparently  more 
accurate  one  given  in  the  la?>l  chapter. 


OKDIiXARY  //WA'  HIGIIU'A  V-HIUDGES. 


89 


In  this  method,  when  the  proper  proportion  of  width  to  dei^th 
ol  bars  is  adhered  to,  the  diameter  of  the  pins  will  be  ahnost 
e.^ht-lenths  of  the  depth  of  the  bars,  and  will  be  great  enou-h 
to  res.st  the  bending- moments  ])roduced  by  any  legitima^'te 
metliod  of  packmg.  Moreover,  after  the  diameters  of  the  pins 
have  been  determined,  the  ehord  ean  be  packed,  if  it  be  advisa- 
ble, so  as  to  reduce  the  bending-moments.  This  supcrabun- 
<lance  of  strength  in  the  pins  is  obtained  at  the  expense  of  a 
slight  increase  in  the  weight  of  iron  ;  and  the  increased  sizes 
ut  heads  for  diagonals  can  do  no  harm,  because  they  do  not 
enter  any  limited  space,  as  do  the  heads  at  their  other  ends 

J5ut  if,  by  a  skilful  arrangement  of  the  packing,  vvc  can  so 
reduce  the  bending-moments  on  the  pins,  that  the  diameters 
ma)-  be  made  small,  and  the  proportion  of  width  to  depth  of 
bars  larger  than  that  found  in  the  last  chapter,  the  pins  may 
not  be  as  strong  as  wc  imagine  them;  for  we  cannot  be  sure 
that  al  the  bars  are  going  to  pull  as  we  have  assumed  that  they 
w.  .  It  may  be  that  one  of  the  outer  bars  is  a  trifle  long,  and 
will  not  pull  at  all  until  the  others  are  well  stretched  :  what 
then,  becomes  of  our  calculated  bending-moments  ? 

Any  one  of  them  may  be  so  greatly  exceeded,  that  the  pin 
will  be  strained  beyond  the  elastic  limit,  and  will  bend  percepti- 
bly, so  changing  the  distribution  of  stress  in  the  panel  that  one 
or  more  of  the  bars  also  may  be  strained  beyond  the  clastic 
limit. 

i^ut  if  the  pin  be  large  enough,  or  more  than  large  enou-h 
.t  cannot   bend   perceptibly  :  consequently  the  distdbution"of 
stress  will  be  much  more  uniform,  even  if  the  bars  be  of  shVhtlv 
unequal  lengths.  ^     ^ 


90 


OJW/.WlAy  JROA-  UIGIIWAY-BRIDGES, 


■   I 

J,. 

CHAPTER   XII. 


RIVETING. 


The  subject  of  riveting  is  one,  which,  like  that  of  pin  propor- 
tioninf^  has  never  received  its  dr.e  amount  of  attention  from 
bridge  designers.  Many  structures  otherwise  very  strong  arc 
extremely  weak  in  detail,  owing  to  the  insufficient  numlu'r 
of  rivets  employed  in  the  connections  and  to  their  improper 
arrangement.  The  principal  rules  for  riveting  have  been  given 
in  Chapter  II.,  pp.  17,  iS. 

Rivets  should  be  proportioned  for  bending  and  for  bearing 
pressure  ;  i.e.,  for  any  given  connection,  the  number  of  rivets 
necessary  to  resist  properly  each  of  these  stresses  should  be 
determined,  and  the  greater  number  chosen. 

Tables  XXXVI.  and  XXXVU.  give  the  working  bending, 
moments  and  permissible  bearing-pressures  for  bridges  of  Class 
A  and  for  those  of  Classes  B  and  C.  For  the  lateral  systems  kA 
both  classes.  Table  XXXVII.  is  to  be  used.  In  these  tables 
the  first  and  second  horizontal  lines  of  vulgar  fractions  and 
decimals  give  the  widths  of  bearings  ;  and  the  other  horizontal 
lines  in  the  portions  pertaining  to  bearing  give  the  working 
bearing-stresses  for  rivets  of  different  diameters.  The  rest  ot 
the  tables  needs  no  explanation. 

The  sizes  of  rivets  ordinarily  employed  for  highway-bridges 
are  from  five-eighths  to  three-cjuarters  of  an  inch  ;  though  half- 
inch  rivets  are  used  for  very  light  channels,  and  seven-eighths 
inch  rivets  for  very  heavy  ones. 

The  weight  of  a  pair  of  rivet  heads  for  any  diameter  can  be 
found  in  Table  XXIX.     It  is  well  to  memorize  the.se  weights. 

Where  two  plates  are  riveted  together,  the  rivets,  driven 
when  hot,  contract,  or  tend  to  contract,  in  length  when  cooled. 


pin  propor- 
L'lition  from 


ir  improper 


ORDIXARV  IRON  HIGHWAY. nRiPGES.  g, 

thus  drawing  the  plates  together,  and  produeing  a  friction  which 
It  IS  necessary  to  overcome  before  shear  can  come  ui^on  the 
rivets.  Whether  this  friction  will  continue  indefinitely  is  doubt- 
ful, for  rivets  occasionally  become  loosened  when  the  structure 
IS  subjected  to  oft-repeated  loads  :  so  it  is  not  legitimate  to 
depend  upon  the  friction  in  order  to  reduce  the  number  of 
rivets.  I'erhaps  it  is  on  account  of  this  factor  that  rivets  are 
seldom,  if  ever,  proportioned  to  resist  the  bending-moments 
that  come  upon  them,  notwithstanding  the  fact  that  it  is  this 
last  consideration,  which,  in  most  cases,  should  determine  the 
number  of  rivets  to  be  employed. 

Again  :  if  the  friction  were  to  be  depended  upon,  it  would  be 
only  right  to  allow  for  the  initial  tension  on  the  rivets,  which 
tension  is  sometimes  great  enough  to  force  off  the  heads 
_    It  will  probably  have  been  noticed  by  the  reader,  that'  shear- 
mg-stress  upon  rivets  has  been  omitted  altogether  from  con- 
sideration.    The  author  would  hesitate  before  making  the  broad 
assertion  that  rivets  cannot  shear,  although  it  is  probable  that 
bending  is  the  stress  which   ruptures  rivets  that  are  generally 
considered  sheared.     This  much,  though,  he  will  statl-  as  the 
result  of  both  theoretical  investigation  and  many  practical  cases 
ot  designing,  that,  xvhen  rivets  arc  proportioned  foy  bcndiug  aud 
bearing,  they  ,vill  have  more  than  snfficient  strenq-th  to  resist  shear 
Sharp  edges  on  rivet  holes  will  certainly  cut  the  rivets,  but  this 
IS  not  shear  proper ;  and  it  may  be  possible  that  there  is  a  cer- 
tain kind  of  fi.vedness  about  a  well-driven  rivet  which  will  make 
the  bending-moment  less  than  its  calculated  value 

Should  the  reader  wish  to  verify  the  statement  concernino- 
bending  and  shearing  stresses,  he  can  do  so  by  using  an  intei" 
sity  of  shearing-stress  of  three  tons  for  bridges  of  Class  A,  and 
one  of  three  tons  and  three-quarters  for  those  of  Classes  B  and  C 
1  he  theoretical  proof  is  identical  with  the  one  for  pins  given  in 
Chapter  X. 

"Countersinking"  is  a  term  used  to  denote  the  sinkino- of 
nvet  heads  mto  the  plate  so  as  to  make  them  flush  with  its 
surface.  The  least  allowable  depth  for  the  countersinkino-  is  a 
quarter  of  an  inch,  and  the  least  thicknes.s  of  plate  used  for  this 
purpose  should  be  three-eighths  „f  an  inch  :  fur  rivets  e.xceedin^^ 


92  OKDLXANV  /AV.V  IIIGUVVAY-HRIDCES. 

three-quarters  of  an  inch  in  diameter,  these  dimensions  should 
be  increased  by  an  eighth  of  an  inch.  Rivets  may  be  counter- 
sunk at  one  or  both  ends. 

Making  parallel  rows  of  rivets  staggered  avoids  unnecessary 
weakening  of  the  parts  riveted  together. 

There  has  been  much  discussion  as  to  whether  punched  or 
drilled  holes  are  preferable  ;  the  general  conclusion  being,  that 
drilled  holes  weaken  the  plates  less,  and  when  slightly  counter- 
sunk,  so  as  to  avoid  sharp  edges,  do  not  increase  the  shear  upon 
the  rivets,  but  that  punched  holes  arc  so  much  more  economi- 
cal as  regards  shop-work,  that,  when  properly  made,  they  are 
preferable  to  drilled  ones.  The  improvements  made  of  late 
years  in  riveting-machines  have  increased  the  efficiency  of  work 
with  punched  rivet  holes. 

Should,  for  any  reason,  it  ever  be  necessary,  in  bridge  design- 
ing,  to  put  a  rivet  through  a  plate  whose  thickness  is  greater 
than  the  diameter  of  the  rivet,  the  rivet  hole  should  be  drilled. 

Machine  riveting  is  preferable  to  hand  riveting,  but  there  are 
cases  when  the  latter  has  to  be  employed. 

Field  riveting  is  nearly  always  inferior  to  shop  riveting. 

When  a  stress  is  transmitted  from  one  plate,  through  one  or 
more  plates,  to  another  plate,  the  number  of  rivets  must  be 
increased.  The  rule  given  by  Weyrauch  is,  that,  "for  every 
single  shear  connection,  the  indirect  force  transferrence  requires 
for  m  intermediate  plates  ;;/  -f  i  times  as  many  rivets  as  for 
direct  transferrence."  Keeping  this  in  view,  the  designer  will 
avoid  using  more  than  one  flange  plate  in  floor  beams,  or  more 
than  one  plate  for  covering  the  channels  of  the  top  chord. 


ORD/xXARy  //WA-  HlGimAV-URWUES. 


93 


miecessary 


CHAPTER  XIII. 

PROPOKTIONING   OF  OTHER  DETAILS. 

The  sizes  of  stay  plates  used  at  the  ends  of  systems  of  lat- 
ticin-  or  double-riveted  lacing  are  given  in  Tabic  XXXII  ,  and 
the  sizes  of  those  used  at  the  ends  of  systems  of  single  riveted 
lacing,  in  Table  XXXIII.  The  headings  of  these  tables  fully 
explain  their  use. 

Stay  plates  are  to  be  employed  at  the  middle  of  posts  {vide 
Plate  II.,  Fig.  15)  when  the  diagonals  are  halved,  and  connected 
by  pins  passing  through  the  posts  ;  their  sizes  being  taken  from 
the  before-mentioned  tables.  Stay  plates,  if  they  can  be  so 
called,  are  also  to  be  used  on  the  lower  portal  struts,  for  the 
purpose  of  attaching  the  knee  braces. 

Pin  bearings  are  .sometimes  figured,  counting  in  both  re-en- 
forcing plates  and  web;  but  the  latter  is  often  omitted.  This 
would  be  necessary  when  the  holes  in  the  web  are  bored  inde- 
pendently  of  those  in  the  re-enforcing  plates,  for  then  it  is  very 
inij'iobable  that  the  different  holes  will  coincide;  but,  when  the 
re-enforcing  plates  are  riveted  to  the  web  before  boring,  such 
a  precaution  is  not  only  unnecessary,  but  is  a  waste  of  material 
Py  consulting  Table  XXVIII.  can  be  found  at  a  glance, 
accurately  enough  for  all  practical  purposes,  the  thickness  of 
web  of  any  Union  Iron-Mills  channel  bar,  when  the  wei-ht  is 
given,  or  vice  versa.  '^ 

Where  re-enforcing   plates  act   also  as  splice  plates,  there 
should  be  one  on  each  side  of  the  web  in  order  to  insure  a  crood 
substantial  joint ;  although  the  practice  in  the  building  of  small 
bridges  IS  to  omit  the  outer  plate  when  the  pin  bearing  does  not 
demand  its  use. 

The  length  of  a  simple  re  enforcing  plate  depends  upon  the 


ill 

m 

94 


ORDINARY  IRON  IJIGHWAY-BRIDGES. 


miinbcr  of  rivets  roquircd,  and  is  thus  determined,  l-'ind,  by 
dividing  tlic  stress  given  on  the  chagram  of  stresses  between  the 
various  thicknesses  of  iron  which  constitute  the  bearings,  the 
amount  of  stress  which  the  plate  considered  is  to  carry.  It  is 
well,  though,  to  make  a  liberal  allowance,  say  twenty  per  cent, 
^or  the  possibility  that  the  stress  may  not  be  divided  propor- 
tionately to  the  thicknes.ses.  Ne.xt  multiply  the  stress  so  ob- 
tained by  the  perpendicular  ilistance  between  the  central  plane 
of  the  re-enforcing  plate  and  that  of  the  plate  or  web  reen- 
forccd  :  the  product  will  be  the  moment  of  the  stress  upon  the 
re-enforcing  plate  Divide  this  moment  by  the  working  bend- 
ing-moment,  taken  from  Table  XXXVI.  or  XXXVII.,  for  a 
rivet  of  the  diameter  to  be  employed  for  the  connection  :  the 
quotient  will  be  the  number  of  rivets  required  to  resist  bend- 
inc:.  Next  find,  from  one  of  the  same  tables,  the  working  bear- 
ing-strcss  for  one  of  the  rivets  upon  a  plate  of  the  thickness 
of  the  re-enforced  plate  or  web,  and  divide  it  into  the  stress 
which  the  lallcr  carries  :  the  quotient  will  be  the  number  of 
rivets  requiretl  to  afford  sufficient  bearing.  The  greater  of 
the  two  numbers  thus  obtained  is  the  one  to  be  employed. 
Ne.xt  make  to  scale  a  drawing  of  the  re-enforcing  plate,  laying 
out  the  rivets,  if  it  be  possible,  symmetrically,  and  thus  deter- 
mine the  length  of  the  re-enforcing  plate.  In  case  of  a  re- 
cnforced  pin  hole,  if  the  diameter  of  the  hole  exceed  one-half 
the  width  of  the  plate,  it  will  be  necessary  to  jiut  more  rivets 
in  front  of  the  pin  hole  than  behind  it ;  the  ratio  of  the  num- 
ber in  front  to  the  whole  number  being  equal  to  that  of  the 
diameter  of  the  hole  to  the  width  of  the  plate. 

The  method  of  proportioning  splice  plates  or  connecting 
plates  is  somewhat  similar.  For  instance,  let  us  take  the  jilates 
at  a  joint  in  the  top  chord  ;  which  joint,  for  reasons  to  be  stated 
in  Chapter  XVIII.,  is  always  to  be  placed  a  few  inches  to  that 
side  of  the  pin  hole  farthest  from  the  middle  of  the  span.  The 
stress  on  the  portions  of  the  plates  to  this  side  of  the  joint  is 
that  due  to  the  stress  in  the  panel  where  the  joint  occurs  ; 
while  that  on  the  other  portion  of  the  plates  is  due  to  the  stress 
in  the  next  panel  towards  the  middle  of  the  span.  The  number 
of  rivets  on  each  side  of  the  joint  will  be  dependent   upon  the 


ORDIA'ARV  IROX  niCHlVAV-HRlDGES. 

.trcsscs  carried  by  the  channel  bars  of  the  two  adj 


95 


'I'll 


le  simplest  way  to  (ind  the  stress 


ply  its  area  by  the  intensity  of  working-st 


acent  panels, 
on  any  channel  is  to  miilti- 


from  either  Table  X.  or  XI.     Th 

equally,  or  otherwise,  between  the  outer  and 

splice  the  abuttinj,^  channel 

sary  to  resist  bendiu';-  and  be 


ress,  which  was  fouml 
is  stress  is  then  to  be  divided 


inner  plates  which 
s ;  and  the  number  of  rivets  iieces- 


uinj;-  are  to  be  ascertained  in   tl 


manner  explained  for  re-enforcinj;  j)lates. 

To  determine  the  length  of  a  cover  plate,  find  in  th 
manner  the  number  of  rivets  ///.„/  each  su/c  of  the  joint,  which 
-111  take  up  the  stress  carried  by  the  chord  i)late,  and 


le 


e  same 


the  cover  plate  with  th 
by 


plate,  and  lay  out 
c  rivet  si)acing  to  scale.     The  stress  car- 


ried by  the  chord  plate  is  equal  to  its  .sectional 


area  multiplied 


by  the  intensity  previously  found  for  the  channels. 

At  the  hip  joint  it  is  obviou.s,  that,  where  the  chord  and  batter 
brace  are  hni-ed  upon  the  pin,  the  resultant  of  the  thrust  in  the 
battrr  brace  and  the  pulls  in  the  diagonals  and 


^•(| 


iial  the  thrust  u 


poll  the  chord,  and  that  the  be 


figured  for  this  thrust;   but,  where  tl 
section  of  the  splice  plates  mu.st   answer   two   ...,..,_ 
hrst,  their  area  (neglecting,  on  account  of  its  bein- "be 
citect  of  the    cover   plate)    must    b 


verticals  must 

aring  must  be 

icy  are  not   hinged,  the 

requirements  : 

nt,  the 


10   sufficient    to   transfer  t 


the  chord  a  stress  equal  to  that  in  the  first  panel  ;  and 


o 


that  the  pin  bearing  be  sufficient  { 


se 


cond. 


sioiiy  in  the  diagonals  aiu 

length  of  the  cover  i)late  at  the  h 


or  the  resultant  of  the  t 


en- 


It  carries  no  stress,  simply  ad 


verticals  meeting  at  the  hip.     The 
ip  cannot  be  calculated  ;  for 


md  keeping  the  rain  therefrom 


Iding  to  the  rigidity  of  the  joint, 


It  the  posts  be  figured  f( 


ate  of  the  chord 


)r  one  fixed  end,  th 


nocting  plate  for  the  post  ;   and 


can  be  extended  downward  to  act 


e  inner  splice 


as  a  con- 


ciiuugh  rivets  used 
ail  th 


in   this   case  there   must    be 


Ml  respect  to  bearing  and  bending  to  transfei 


i)lat 


e  compression  in  the  post  to  the  chord  by  th 


c,  under 


th 


e  coniiectiiiL'- 


e  su 


llO     11 


pposition  that  the  ends  of  the  post  channel,^ 


tnlich 


llDo 


ot  touch  the  flanges  of  the  chord  channels       If 
so  much  the  better;  but  it  would  not  be  safe 


slmuk 


II  their  doing  so.      The  thick 


they  do 
to  count 


be  such  that  it  would  not  bend  bet 


ickness  of  the  connecting-p]at( 


ween  the  end  of  th( 


w. 


96 


f'/.7'/.\'./A')'  /h'o.y  ii!i:iiw.\y-nRiiH;i:s. 


post  and  tlic  pill  IkiIc  wlu-n  the  post  would  be  on  the  point  of 
riiptiiic  by  compression.  Where  the  ends  of  the  posts  ;ire 
fi^^ured  iiin;j;cd,  which  is  a  decidedly  better  construction,  the 
cxtennion  plates  pass  inside  the  splice  plates  of  the  chord,  and 
are  attacheil  to  the  pins.  As  before,  there  must  be  enough 
rivets  to  transfer  the  stress  in  the  posts  to  the  plate. 

The  thickness  of  the  re-enforcing  plates  at  the  lower  end  of  a 
post  is  determined  '  y  the  bearing  recpiired,  and  their  length  in 
the  manner  already  described,  It  is  l)etter  to  place  these  plates 
on  the  inside  of  the  posts  ;  then,  if  the  llaiiges  of  the  channels 
be  i)artially  cut  away,  an  extra  plate  (at  least  three-eighths  of  an 
inch  tiiick)  can  be  placed  on  the  outside  of  each  channel.  The 
reason  for  cutting  away  the  bottoms  of  the  post  channels  is 
merely  to  [jack  the  cliord  more  closely,  and  thus  reduce  the 
bending-moments  on  the  pins.  lUit,  if  the  method  of  pin  pro- 
portioning given  in  Chapter  XI.  be  adopted,  the  necessity  for 
cutting  away  the  channels,  to  any  extent,  vanishes  ;  for  at  the 
middle  of  the  span  the  web  stresses  are  so  small,  tliat  their 
moments  are  neglected,  and  the  pins  at  the  feet  of  the  other 
posts  have  an  excess  of  strength. 

In  high  double  intersection  truss  bridges  with  long  panels, 
the  diagonals  become  so  long,  that  it  is  convenient  to  halve 
them,  and  connect  the  halves  by  pins.  It  is  then  advisable  to 
let  these  pins  pass  through  the  webs  of  the  ]i()st  channels  where 
the  diagonals  cross,  for  the  latter  then  tend  to  stiflen  the  pcjsts. 
If  intermediate  struts  also  be  used  at  the  middle  of  the  trusses, 
the  posts  can  be  figured  for  half  length,  with  both  ends  hinged. 
On  account  of  the  stretch  of  the  main  diagonal,  there  would  be 
a  tendency  to  deflect  the  post.  If  the  diagonals  were  forty-two 
feet  long,  the  stretch  of  the  upper  half  of  them  would  be  about 
one-eighth  of  an  inch  ;  so  that,  to  avoid  this  objection,  it  will 
be  necessary  to  elongate  the  pin  hole  that  amount  on  the  lower 
side,  in  the  direction  of  the  main  diagonal.  The  pin  V  I'-s 
should,  of  course,  be  well  re-enforced  in  order  to  compen- 
sate for  the  material  cut  from  the  channels.  The  stretch  of 
the  counters  being  less  than  that  of  the  main  diagonals,  and  the 
posts  crossed  by  the  heavy  ones  generally  having  an  excess  of 
strength,  it  is  <iOi  uccessary  to  elongate  the  pin  holes  in  the 
direction  of  tl.e  1  ;.   'th  'if  the  counters. 


('/^•n/x.i/n-  ,A'ox  iin:nuAv_,a„nr.i-:s. 


In  nearly  all  iron   l)ri<l-,>s  (Ir.  hatti-r  I 
•nils  fixed  at  the  pedestals  ( 


97 


i.e.,  tliev  are  ri 


nraees  are   made  with 


"e   plates),    although    hinj,^,.^    p^dc-stal 
tlie  aJvanta^^'  j^ained   by  tliel 
fftrndy  distributed  pi 


r  use   is  the  certa 


(idly  attached  to  thi 
'110    not    unknown 


essu 


re  on  the  rollers,  and  the  disad 


inty  of  a  uni- 


a  Kroat  nierease  in  the  section  of  the  batter  1 

I  he  shoe  plate  can  be  attached 
I'.v  bent  plates  on  the  inside,  the 
iif  channels,  with 


vanta;:c 


>races. 


t«)  the  batter-brace  channels 
outside,  or  both,  or  by  pieces 


oiic  flange  removed,  placed  on  tli 


C'  inside,  and 
:haii- 


I  .  ami  U,,„,„ ,  .|,,ir  nances  t„  ,1,.  ,h„c.  „la, 
"'it^'  IV.     The  lower  end  of  the  b 
tiiMied  up  horizontally,  an 


plate,  as  shown  on 
:itter-brace  plate  should  be 


Tl 


ie  area 


of 


iveted  to  the  shoe  plat 
a  section  of  the  connecting  channel 


'"a.le  by  a  plane  perpendicular  to  the  d 
hraee  should  be  ecpial  to  the  area  of 


>r  greater  if  the  shoe 


\\"i'lcl  afford  ;  and  there  should  b 


or  plate 

irection  of  the  batter 

one  batter-brace  channel, 

an   this 


pin   require  greater  bearin-  th 


stress  from  the  batter-bracc  channel  to  th 


'^  enough  rivets  to  transfer  thi 


>i"  I>late.     Should  the  b 


shoe  plates,  as  they  ought  to  do,  th 
iccessary;    but   such  a  1> 


:itter-brace  channels  bcai 


10  connecting  channel 
against  the 


ere  will  be  more  rivets  th 


Details  of  sh 


•earing  should   not   b 


an 


oes  are  shown  on   i'lates    II.,   HJ.,  ly 


e  counted   upon. 


The  rules   for  proportionmg  shoe 
,!;i\eii  on  p.    1 6. 

very  good  connection  for  the  h 


rollc 


and   V'l. 


r,  and   bed  plates,  c 


iro 


I'lates  III.  and  IV.      Th 

I'lider  one  passing  entirely  below  th 


P  joint  is  the  one  shown  on 
0  Miner  si^lice  plate  has  five  sides,  the 


:Ue  is  cut  to  fit  closely  to  the  wei)s  of 


10  joint  ;  and  the  outer  splice 


hnice  channels,  bei 


the  chord  and  batt 


DC 

thi? 


Is  and  the  rivet  heads  th 


'  ■^•'■'  ""  ^"'-  euuKi  anti  batter- 

ng  made  as  wide  as  the  flanges  of  the  chan- 


s  detail  is,  that  it  re 


lerem  will  permit      The  objection 


uiother  good  detail  for  tl 


■quires  a  good  deal  of  field 


to 


rivet  inc. 


''late  II.      Ifereth 
"f  the  chord,  and 


us 


joint   is  that  shown 


in  F 


'g-  14. 


wh 


plates  riveted  to  th 
those   on 


ere  are  two  connecting-plates  on  the  outside 

t^vo  on  the  mside  of  the  batter  brace,  through 

se  on  the  chord  abut  against 


ieh  the  pin  passes.     Tl 


U) 


-_  outside  of  the  batter-brace  channels";  and 


the  batter  brace  abut 


against  plates  riveted  to  the 


'A7V.\'./A')     /AV'.\-    l/liliniW  ! 


-llh'/PilF.S. 


itisu 


le  of  t!u>  chord  cliaiincls,  all  ahuUin^  surface 


hcini 


planed 


to  fit  exactly;  so  that,  when  the 


in   is  driven   into  place,  tlie 


th 


t  will  be  as  ri-id  as  if  it  were  nveled 


whole  joui 

<letail  demands  neat    worknuuis 


Of  course  this 


hip,  and  is  consequently 


some- 


what expensive 
counlerbalances 


but  the  satisfactory  result  attained  more  than 
the  extra  cost  of  the  shop-work,  and   there  i^ 


no  neee 


ssity  for  figuring   on 


a    hiiiLrei 


i    ^-xuX  at    the   hip    when 


Mdpoi 
:hord. 


lionuu 


•ooil  me 


•hor 


the  batter  brace  and  the  end  panel   of  the  top 

thod  of  attaching  the  upper  lateral  struts  to  the 
which  is  illustrated  on  Plates  II.,  IV, 


the  foUowini 


hortis  IS  ine  iomuwhil;,  uim..  .--   ...-■•- 

nd  VI.      Let  the  web  of  the  upper  channel  lie  upon  the  cover 


plate  of  the  chord,  extendi n 


thereto 


ami 


let  the  uiK 


ler  f; 


beiiv'  turned  downwan 


faces  (. 


if   the  lower 


Ham 


length  of  the  lowei    c 


pie  of  inches  shorter  than  the  clear  roac 


ccni 


The  coiuieclion  is  mai 


to  its  outer  edge,  and  be  riveted 
ice  of  the  lower  channel,  its  ilanges 
lie  in  the  same  horizontal  plane  as  the 
:s  of   the  toji  chord  channels.       The 
f  the   lateral   strut  should   be  a 
way  of  the  bridge. 


\annel  o 


tter 


the  head   being  rive 


Ic  by  a  plate  in  the  form  ol   the  le 
led  to  the  lower  Ilanges  of  the  inner  cluatl 


Is,  and   the   stem    pass 


channels, 

lower  channe 

be  riveted.     The  thic 

of  an  inch,  and  the  \\'< 


iiu 


between   the    tlanges   ( 


if    the 


1  of  the  lateral  strut,  tt)  the  we 


)  o 


f  which  it  is  to 


kness  of  the  T-plate  shoultl  be  five-ei-hths 


ntrant  angles  siu 


)UU1 


be  rouiulec 


oil  with 


a  radius 


ol  an   inch  am 


half  or   two   inches 


The   wiillh   ot 


the  stem  s 


louk 


1h'  matle 


is  ureat  as  the  elis 


lance   betwt'eii   the 


f  the   lateral   >lrut  will   permit,  ami   Lli 


flanges  o 

equal  to  the  width  o 


It   of  the   head 


f  the  tlanges  of  the  chord  channels 


Tl 


le  num 


her  of  rivets  tor  either  stem  or  he: 


tl  must  be  calcu 
1  ilcd  for  bending  and  bearing  resistances  corresponding  to  the 
..•reatest  stress  that  couul  ever  come  upon  the  channel,  which 
stress  is  to  be  calculated  by  multiplying  the  area  of  the  channel 
by  the  intensity  found  in  Table  XI. 

'a  ..ood  connection  lor  the  iiUermediale  slruts  to  the  posts 
is  by'means  of  two  l.enl  plates  at  each  end  ol  the  strut  (vur 
ITites  IV.  an  ;  \-l.).  One  le.'  of  each  plate  is  riveted  to  the 
web  of  the  inner  ch.nme!  of  the  post,  and  the  other  to  the  web  nt 
the  I-beam,  which   i>  placed   horizontally      The  vibration  rods 


ORniXANY  tRox  jinnin-Av-nRiiKiF.s.  gg 

arc  attached  by  holts  that  pass  thro„,-h  the  two  connecting- 
plates  and  the  wel)  of  the  I-heanv  The  connection  at  th^^ 
upper  cm\s  of  the  vibration  rod  may  be  similar,  if  tlie  width 
nl  the  T  connectmg-plate  be  great  enough  to  permit  of  the 
jiassage  of  a  bolt. 

At  tlie  intermediate  strut  connection,  there  should  be  cnou"-h 
nvels  used  ,n  respect  to  ben.ling  and  bearing  to  transfer  the 
calculated  stress  upon  the  strut  to  the  connecting-plates 

If  there  be  but  one  portal  strut  at  each  end  of  the  span    it 

may  be  connected  to  the  batter  brace  by  two  large  bolts  passi'n. 

through  a  jaw  plate,  as  shown  in  Mg.  , ,,  Plate  II.     These  bolts 

■nay  have  square  heads  placed  so  near  the  sides  of  the  jaw  that 

t   ey  cannot  turn,  the  nut  having  to  be  screwed  upon  the  ins.de 

'       ho    atter  brace.     But.  if  there  be  two  portal  struts  at  each 

--'  "f  the  .span,  the  channels  are  to  be  turned  around  ninety 

<legrees.  an<I  brought  nearer  together;  so  that  it  will  be  better 

n  use  exter.or  bent  plates  attached  to  the  flanges  of  the  chan- 

U.s  shown   on   Hates  IV.  and  VI..  in  addition  to  a  single 

lai-e  bolt  through  the  jaw. 

Concerning  the  best  method  of  connecting  the  lower  lateral 

nnls.  there  ,s  much  chversity  of  opinion  ;  although,  in  ninetynine 

cases  out  o    a  hundred,  they  are  attached  to  the  floor  iLml 

wh.ch  are  thus  made  to  act  as  struts   for  the  wind  pressure' 

-Some  brulge  designers  put  bent  eyes  on  the  lateral  ods,  and 
■un     .jsu^^ 

^  ohjec  lonable,  for  two  reasons  :  First,  the  laterals  take  hold 
.he  weakest  part  of  the  beam  ;  and  second,  beu.g  attach.U^ 
-  ;'^  --/'-"  the  pins,  they  permit  of  too  much  vibration, 

•^nothe.cle tad  ,s    o  rivet  two  4  by  6  inch  angles  to  the  web,  and 
;-;:;;^  P-  through  the  six-inch  legs  :  this  is  a  little  better  dm 
In.'  the  .same  objections  apply  here.     Another  is  to  let  the  10  Is 

pass  U..ough  the  webs,  and  through  rods  and  plates  bent  t  ;;;': 
-nc  .ace  ,s  perpendicular  to  the  direction  of  the  lateral  rod 
a-  her  face  parallel  to  it.  and  the  ot-ier  two  end  faces  nr  1  el 
';•  the  web  of  the  beam,  to  which  they  are  riveted.  The^ 
:'''l-  'ons  apply  to  this,  together  with  two  which  are  sti  nTre 
"■1-tant  vz..  that,  as  at  each  connection  there  are  to  such 
"'-- -^'"- lateral  rods  from  adjacent  panels  cri::        h 


II!    Ki  B'ii  1-    ;' 


illirw 


lOO 


O/wrXARV  IROX  UICIIWA  Y-P.RI nc.F.s. 


other  the  lon-itiulinal  components  of  the  stresses  m  tlie  latter 
produce  a  moment  tending  to  revolve  the  beam  about  the  upper 
ed-e  of  the  web.     Then,  again,  the  bent  plates  must  be  made 
solieavy  that  they  would  withstand,  before  bucklmg,  the  ulti- 
mate pull  of  the  lateral  rods ;  and  it  is  very  seldom  that  such 
a  detail  is  made  strong  enough  to  stand  the  ultimate  pull  of  an 
inch  and  a  half  round  rod.     Another  way  is  to  rivet  a  plate  across 
the  top  of  the  beam,  and  two  bent  plates  or  large  angles  opposite 
each  other,  just  below  the  top  flange,  dropping  i)ins  through  the 
jaws  thus  formed.     This  is  the  best  arrangement  yet  employed. 
But  in  the  author's  opinion  all  these  details  are  defective,  for 
the  reason  that  the  lateral  rods  all  take  hold  of  the  floor  beams, 
which    are   simply  suspended  from   the   i^ns   that   are   several 
inches  above  them  ;  so  that,  unless  the  hangers  be  screwed  up 
very  ti-htly,  any  wind  stress  in  the  lateral   rod  will   cause  a 
rockino°at  the  point  of  suspension,  and,  even  if  the  hangers  be 
screwJcl  up  tightly,  the  tcmhncy  to  rock  still  exists.     Ihe  only 
correct  place  to  attach  the  lateral  rods  is  to  the  chord  pins,  ami 
their  stresses  should  not  he  transmitted  through  the  floor  beams.^ 
Then  come  the  questions,  MIow  shall   they  be  transferred? 
and  "  How  shall  the  rods  be  arranged  so  as  to  clear  the  joists  . 
The  detail  about  to  be  described  will  answer  these  questions. 

Upon  the  floor  beam  place  a  stick  of  square  timber  (about 
ei-ht  inches  for  ordinary  highway-bridges),  and  let  the  ends  fit 
into  wrought-iron  jaws,  which  screw  up  against  the  chord  pins  ; 
then  fasten  the  timber  every  few  feet  on  alternate  sides  of  the 
web  by  half-inch  bolts,  to  the  flanges  of  the  beam,  and  rest 
the  joists  on  the  timber.  The  laterals  can  either  be  attached  by 
bent  eyes  to  the  chord  pins  (which  would  be  preferable  if  then- 
diameters  do  not  exceed  an  inch  and  three-fourths),  or  by  ordi- 
nary eyes  to  vertical  pins  passing  through  the  wrought-iro.i 
jaws  In  this  way  the  timber  not  only  acts  as  a  lower  lateral 
strut,  but  serves  to  give  additional  stiffness  to  the  floor  beam; 
although  the  section  of  the  latter  should  not  be  diminished  on 

that  account. 

Now,  what  objections  can  be  raised  to  this  method  ,' 

Some  may  say  that  it  is  a  clumsy  contrivance,  but  that  is  a 

matter  of  taste.     Others  may  suggest   thai   it  reduces  an  no,, 


'^''^'f>/.yANV  //WN  H/GI/ll'AV-B/UDGES.  loi 

structure  to  a  combination  bridge.  Not  at  all,  -  no  more  tlian 
the  emi^loyment  of  wood  for  the  floor  and  joists;  because,  at  the 
same  time  when  the  latter  are  renewed,  the  wooden  struts  can 
be  replaced.  There  is  a  slight  objection  for  short  throu-^h- 
sixms  y,z.,  that  it  reduces  the  headway;  but  it  would  not 
greatly  increase  the  expense  to  add  eight  inches  to  the  depth 
ot  the  trusses.  ^ 

Another  method  of  avoiding  the  difficulty  is  to  rivet  the  floor 
beams  to  the  posts.     But  will  not  this  be  equally  objectionable } 
Certainly  such  a  connection  is  better  for  the  beams,  as  it  par- 
tial y  fixes  their  ends  ;  but  what  about  the  deflecting  effects  of 
u-md  stresses  and  passing  loads  upon  the  posts.'     The  trans 
verse   components  of   the   lateral   rod  stresses  act   with   o-r^at 
leverage,  tor  the  beams  are  always  attached  above  the  boUom 
chords  ;    and  the  weight  of   a  heavy  wagon  coming  suddenly 
upon  the  beam  must  certainly  cause  the  posts  to  vibrate  trans- 
versely to  the  planes  of  the  trusses,  but  to  what  extent,  and 
with  what  injurious  effect  upon  the  posts,  it  is  at  present  im 
possible  to  say.     I.:ven  if  there  be  but  little  known  concern- 
j"g  this  attachment,  it  is  certain  that  a  floor  beam  should  never 
be  riveted  to  only  one  of  the  channels  of  each  post.     Such  an 
arrangement  would  produce  indirect  stresses  of  a  destructive 
character:  consequently  the  posts  should  be  turned  one-quarter 
way  round  in  order  to  let  the  beam  pass  between  them 

••  l.H.r  beams  in  deck  bridges  may  either  rest  upon  the  chords, 
I'o  uing  trom  the  chord  pins,  or  be  riveted  to  the  posts  In 
neither  case  should  they  be  used  as  lateral  struts  when  the 
lateral  rods  are  attached  to  the  chord  pins,  because  of  the  lever- 
age^that  would  be  afforded  to  the  lateral  stresses  to  produce 

It   is  not  customary  to  calculate  the  thicknesses  of  beam- 

'•n.^ci  plates,  for  they  are  usually  made  from  three-fourths  of 

■nchtoanmch    thick    for  ordinary   highwavbridges ;    but 

n|u  cerain  assumptions  their  thicknesses  can' be  calculated. 

tHc  load  on  a  plate  be  consi.lered  uniformly  distributed  over 
^'  l-t.on  between  the  beam-hanger  holes,  and  if  the  flange  of 

;;l;;;'nn>c  supposed   to  take  up  no  bending-stress,  the  plate 
'"■'>  '>^    -nsidered  as  a  beam  supported  at   the  ends,  and   uni- 


lo: 


ORD/XARV  IRO.V  HIGHIV AY-BRIDGES. 


ii 


iMi 


lflW»s 


formly  loaded.  For  instance,  take  the  case  of  a  twenty-foot 
panel  and  an  eighteen-foot  clear  roadway,  the  re-action  at  each 
end  of  the  beam  is  about  nine  tons.  Suppose  the  centres  of 
beam-hanger  holes  to  be  situated  on  the  corners  of  a  four-inch 
square,  and  the  plate  to  be  seven  inches  square,  then  the  bend- 
ing-moment  is 

i)/  =  J  ?F/  =  ^~  X  9  X  4  =  4-5  inch  tons. 

T?  J 

The  resisting  moment  is   — ,-,  where  R  =  5  tons,  /  =  moment 


'^, 


(i 


of  inertia  =  -^JhP  =  {..(P,  and  ^,  =  "■     Equating  the  moments, 

substituting,  and  solving,  gives  <'/  =  about  seven-eighths  of  an 
inch,  a  result  agreeing  with  good  practice.  It  is  almost  need- 
less to  say  that  this  method  is  very  approximate ;  for  the  plate 
is  greatly  stiffened  by  the  rigidity  of  the  flange  of  the  beam, 
while,  on  the  other  hand,  no  reduction  has  been  made  for  the 
beam-hanger  holes. 

Lacing,  or,  as  it  is  often  improperly  termed,  single  latticing, 
is  about  the  most  common  detail  for  keeping  pairs  of  channel 
bars  in  line :  nevertheless,  it  must  be  inferior  to  latticing, 
especially  when  the  lattice  bars  are  riveted  together  at  their 
intersection.  By  inspecting  Tables  XXXII.  and  XXXIII.  it 
will  be  seen  that  a  system  of  lacing-bars  with  one  rivet  at  each 
end  of  a  bar  requires  much  larger  stay  plates  at  the  ends  than 
does    a    corresponding   system    of   latticing   or  double-riveted 

lacing. 

The  actual  sizes  of  lattice  or  lacing  bars  for  any  strut  can  be 
determined  only  by  experiment :  it  is  thought  that  those  given 
in  Tables  XXX.  anci  XXXI.  are  so  strong,  that  the  struts  on 
which  they  are  employed  would  break  in  the  channels  rather 
than  in  the  bars,  and  yet  not  so  heavy  as  to  cause  much  un- 
necessary use  of  material.  It  will  be  seen  also  in  these  tables, 
that  the  requisite  dimensions  of  latticing  and  lacing  bars  depend 
not  only  upon  the  sizes  of  the  channels  which  they  connect,  but 
also  upon  the  distance  apart  of  these  channels  :  this  is  due  to 
the  fact  that  the  bars  are  subject  to  compression  as  well  as 
to  tension.     The  lengths  and  weights  of  latticing  and  lacing 


OKI)/A-AKy  /A'C.\-  JIlCHWAV-liRlDGES. 


103 


I  moments, 


bars  can  be  found  from  Table  XXIX.  It  must  not  be  forgotten 
that  these  lengths  are  to  be  used  for  cstiinalcs  only;  as  they  were 
obtained  from  a  diagram,  and  not  checked  by  calculation. 

The  smallest  trussing-bars  used  should  be  no  less  than  a 
quarter  of  an  inch  by  three  inches,  and  the  bend  for  attach- 
ment should  be  no  less  than  three  inches  long,  so  as  to  permit 
of  the  use  of  two  staggered  rivets.  The  heavier  the  trussed 
bars,  and  the  greater  the  distance  between  them,  the  greater 
should  be  the  section'  of  the  trussing-bars.  At  the  encts  of  a 
s\  stem  of  trussing,  the  bars  should  be  turned  and  attached,  as 
shown  on  Plate  II.,  Fig.  8,  and  on  Plate  VT. 

The  lightest  bracket  used  should  be  no  weaker  than  a  2.1" 
X  2]"  4.9*  angle  iron,  which  section  is  to  be  employed  only 
to  attach  intermediate  struts  to  posts.  Where  there  is  no 
vertical  sway  bracing,  the  stresses  on  the  brackets  are  to  be 
calculated  as  shown  in  Chapter  VI.,  and  the  sections  are  to 
be  proi)ortioned  by  using  the  following  table  of  approximate 
intensities  of  workiuir-stress. 


trut  can  be 


I.KXCril  (1F  STRUT, 
]N   I'KET. 


Intkn^.itiks  of  Wdkking-Stre 


4 
6 
8 


aj"  X  2i"  L. 


3'0 
2.0 


3"  X  3"  L. 

o   - 


jr  X  u"  L. 


4.0 

3-5 

3-0 


The  number  of  rivets  that  connect  the  bracket  to  the  lateral 
strut  and  jjost  must  be  sufficient  to  transfer  all  the  stress  in  the 
bracket  to  each  of  these  members. 

To  prevent  the  pedestal  at  the  free  end  of  a  span  from  slip- 
ping in  the  direction  of  the  length  of  the  rollers,  the  latter  can 
be  notched  about  a  quarter  of  an  inch  in  depth,  for  a  length  of 
about  two  inches  at  the  middle,  and  the  shoe  plate  andVoller 
plate  be  planed  down  so  as  to  leave  projections  which  will 
exactly  fill  the  notches.     This  detail  is  illustrated  in  Plate  VI. 

For  short  spans,  a  sliding-joint  such  as  shown  on  Plate  III. 
is  to  be  used. 


104 


OKi)!.\\un-  /Kox  iin.nwAY-nRiiHiEs. 


When  it  becomes  neeessary  to  anchor  down  the  expandinj; 
end  of  a  bridge,  it  should  be  done  in  such  a  manner  that  the 
shoe  could  not  rise  more  than  an  eighth  of  an  inch  :  thus  the 
projection  on  the  luuler  side  of  the  shoe  plate  will  be  prevented 
from  being  lifted  out  of  the  notches  on  the  rollers. 

l?ed  plates  and  roller  jjlates  should  be  anchored  to  the  abut- 
ments by  rods  with  nuts.  When  the  abutments  are  of  stone,  a 
jrood  method  of  attachment  is  to  drill  holes  therein  just  below 
the  anchor  bolt  holes  in  the  bed  plates,  enlarging  them,  if  prac- 
ticable, at  the  bottom.  Split  the  ends  of  the  anchor  bolts  several 
inches,  insert  small  iron  wedges  in  the  splits,  drive  the  bolts 
into  place,  so  that  the  wedges  force  the  split  ends  apart,  thus 
partially  filling  the  enlarged  bottoms  of  the  holes,  and  pour  in 
molten  sulphur. 

In  figuring  lengths  of  fillers  for  pins,  a  clearance  of  from  a 
quarter  to  half  an  inch  should  be  made,  so  as  to  allow  for  varia- 
tion in  thickness  of  eye-bar  heads,  re-enforcing  plates,  etc.  :  such 
an  allowance  will  sa\-e  a  good  deal  of  trouble  in  erection.  When 
the  end  lower  lateral  strut  is  of  such  dimensions  that  it  will  not 
fit,  without  being  turned  from  the  vertical  between  the  ttanges 
of  the  batter-brace  channels,  filling-rings  can  be  used  between 
the  batter-brace  webs  and  the  ends  of  the  strut.  Such  rings 
will  be  necessary,  if  there  be  four  chord  bars  in  the  end  panel, 
and  the  outer  ones  be  not  let  into  the  channel  flanges  far  enough 
to  lie  against  the  webs. 

In  making  turn  hurkles.  n  little  expense  can  be  saved  by  hav- 
ing only  one  adjusting-end  ;  the  other  having  a  hole,  through 
which  passes  one  end  of  the  rod,  which  is  enlarged  into  a  heail. 
One  advantage  of  this  style  is,  that  the  turn  buckle  can  never 
be  lost  from  the  rod.  Such  a  turn  buckle  should  always  be 
used  on  portal  vibration  rnds,  for  a  reason  that  will  be  given  in 
Chapter  XX. 

Jaws  are  not  a  very  desirable  detail,  although  so  convenient 
that  they  are  often  employed.  In  the  first  place  they  have  not 
a  pleasing  effect  to  the  eye;  and  in  the  second,  on  account  of 
the  bent  plates,  are  iiaole  m  ou  wcakci  lium  rnight  be  esti- 
mated. If  the  flaii.i;es  of  the  channels  be  cut  away,  as  is  some- 
times unavoidable,  the  jiiw  plate,  from  the  cut  flanges   to  the 


iM 


O/W/A'.l/CV  JA^OX  HlGHH-AV-HRinGES.  ,05 

bend,  should  be  able  to  resist  more  compression  than  the  rest 
o  the  s  ru  .  Such  a  detail  occurs  often  on  the  ends  of  the 
struts  wh.ch  keep  the  pedestals  apart.  It  is  generally  diffleult 
to  make  a  satisfactory  design  for  this  member,  as  it  interferes 

.'^V";?'l'    rJ^''^'^  ''^^'  '°"^''"  '^^^•■'-^^  ^y^^*^"^  P'-eviously 
(lescrd)ed,  all  the  difficulty  vanishes 

Concerning  the   proportioning  of  eye-bar  heads,  there  is  a 
variety  of  both  op.n.on  and  practice.     Many  specifications  call 
nr  a  see  .on  a    the  eye  ec,ual  to  one  and  a  half  times  that  of 
he  bar  for  welded  bars,  or  one  and  a  third  times  the  same  fo 
ammered  eyes,  no,:  taking  into  account  the  effect  which  the 
Ifcrent  rat.os  of  chameter  of  pin  to  width  of  bar  have  upon 
t  e    s  reng  h  0     the  eye.      Specifications  for  the  better  class 
'      -t     radroad  and  highway  bridges  have  of  late  made  this 
d..s  .nctu.n     but  there  seems  to  be  some  uncertainty  as  to  wha 
.s  the  e.xac    effect  of  each  ratio  upon  the  strength.     On  p.  20  i 
given   a  table  for  sizes  of  chord  heads,  prepared  from  actua 
experiments  by  C.  Shaler  Smith.  C.E..  who  is  considered  th 
X.St    Amencan    authority   upon    all    matters   connected    with 
he  des.gnmg  of  bndge  superstructures.     The  subject  of  chord- 
head  proporfoning  is  further  treated  in  Chapter  XVIII 

]>cnt  eyes  do  not  make  a  very  good  detail,  but  are 'such  a 
conven.ence  that  they  are  often  used  by  good  desLniers  If 
he  .ameters  of  the  rods  do  not  e.xceecl  o^ne  inch  a  hre 
1-nths,  here  ks  no  objection  to  using  such  eyes.  The  prin  pal 
l;-t  to  be  ra.sed  against  them  is  because  o^  the  eccentri:^^ 
^^  iK.y  g,ve  upon  the  pin  nut.  This  objection  n.ay  be 
n,o.ed  by  usmg  e.ther  extra  large  nuts,  or  the  detail  shou".  in 

:;;■'■  '^'''^'  ;r'  ^".""-^-"  "^  ^'l^tes  H.  and  IV..  in  which 

bcKt  eyes  pull  aga.nst  a  piece  of  channel  riveted  to  the 

M  ut      A  stdl  greater  miprovement  is  shown  on  Plate  VI.   in 

;vh.ch  a  p.ece  of  bent  plate  is  substituted  for  the  channel  •  t'h 

orm.  s  o   more  rivets  in  the  connection,  and  avoids  the  pc'^^ 

h.h.M.t^ha^^.g  to  .nsert  a  filling-phue  between  the  channjl  and 

In  connection  with  this  detail,  on  Plate  VI.  is  another  and  a 

athe,    peculiar  one.     The  plate,  which   was  originally   in  the 

""•'"  ^'f  the  letter  T,  i.s  bent  .so  that  the  stem  n^a^Tbe  r  veted  to 


io6 


oh'p/.y.u^y  i/^'o.\  iih'.iiivA v-nRiiHuis. 


the  strut  c'lianiu-ls,  and  the  lu-ad  may  afford  a  lu-arinj;  for  the 
vihration-iixl  pin.  '\'\\\^  i-oniici-tion  is  to  hi-  used  whc-n  llic  hit- 
oral  strut  chaiuu' 


Is  aiv  so  small  that   ihoiv  is  no  room  for  a 


pin    to    pass   thront;)!    tho   coniu 


tin-  lowi'i'  I 


itinj;-   T-plalo   uliirh   attache's 

th 


hanm-l.      W'lu'ii,  in-causc  of  th^-ir  lar^o  (lianK't(.T,  tlu 


loWi,'!' 


ati'iai   roils   i. 


annol   ho  attached   lo  the  chord  pins,   1 


)nt 


must  he  connected  hy  vertical  pins  passin;^,-  throu^ii  the  lateral 
strut  jaws,  they  must  he  made  lo  pull  on  the  midille  point  of 
•h  of  the  latter  pins  hy  usini;  a  ilouhle  eye  on  one  of  the  rods, 

huLie  enough   to  admit   the  eye  of  the 


eai 


\\r 


h  a  space  hetween 


otiier  roil 


Phis  is  to  avoid  al 


tendency  to  rotate    the  lateral 


strut  ahout  its  a\i«;.     The  rods  can  he  retained  in  place  hy  tillers 


ahove  ani 


hel 


o\v, 


)Ui;h 
>f  the  moment  of  the  lon-;itudinal  com 


With  this  detail.  thtMc  is  a  tendency  to  hreak  the  jaw  tlin 
the  pni  holes,  hecausc 


ponen 
1 


I  of  the  Literal  rod  stress:  the  jaw  plate  must   therefore 


■)e  ma( 


le  wide  enoui;h   to   properly  resist    this   moment 


Th 


easies 


I  way  lo  proportion  the  plate  is  to  assume  its  dimensions 


and  to  find  its  resistance 


lo  hendinu',  neglect ini;  the  area    lost 


hy  the  pin  holes  (which  area  is  close  lo  the  neutral  surface), 
anil  makini;  up  for  the  omission  hy  providin--  a  little  extra 
resist, mce. 


To  illustrate  the  ir.c 


Ihod,  let   us  lake  a  two-inch   lateral   ro 


makimj,'  an  an 


liusses,  aiu 


ole  of  forty-live  de.t;rees  with   the   planes  of  the 
1  lei  the  distance  hel  ween  centres  of  pin  l)earinj;s  Ik- 


si 


\  inches.     The  s 


tress  on  such  a   rod   is   3.14  X  7.5 


tons,   auu   t 


he    l)eiHlini;-momenl    on 


thi 


pin    IS 


X 


•  SS  X  ,> 


.ss.s 


mc 


h  tons,  correspomlini;  {vide  Tahle  XII.)  lo  a  ilia 


me 


ter  o 


if  th 


ree  inches 


and  a  fourth. 


Th 


e  distance  from  the  axis 


of   the   pin    to    the    centr 


e   I 


>f   tin 


iaw   hearmi;-   wil 


he    .ihout 


_|.  j"_|-  i"-|- ;^"  -  5".     The  lon^t;iludinal  component  oi   tin 


stress  on   the   lateral   rod   is   ^3 
the  momen 


55  X  0.7  =  16.5   Ion 


s.  inakiiu 


t  on  the  jaw  ahoul  3  X  16.5  =  S2.5  inch  Ions.     The 
thickness  of  the   jaw  plate  should  he  %\  and  let  us  assume  llio 


Aviillh   to  he  7 
known  formula, 


The  resislinii-moment  is   given 


hy  th 


e  well- 


J/  = 


/?/ 


(>A'/)/x.i/n'  /h'ox  j"c,nu'A  v-nRiDcr.s. 


107 


WlUTC 


A"  =  1 1.25  t„ns,  /  =  /,/;,/3  =  ji,  X  V-  X  (;)•■',  and  d,=l 


Siil)slitutiii<^,  f^ivc's 


M: 


11.25  X  tV^X  V  X  49  X  7  X  2 


1 15  incli  tons,  nearly. 


jaw  thn'UL;li 
^uilinal  com 
st  tlKTcton.' 
nu-nt.  llu' 
(liinciisions, 
U'  area  lost 
ral  siiriacx'), 
little    c.Nlra 


Tlic  (lilfi-iviirc  bctvvcfii  115  and  82.5,  or  32.5  inch  tons,  is  ,t;rcatcr 
than  the  rcsistin<;-monicnt  of  the  material  lo.st  by  the  pin  hole: 
so  the  dimensions  assumed  are  ample. 

U-nuts  are  objectionable  in  every  case;  for,  if  th 


stronir  en 


ey  are  made 


oii-h  to  resist  without   bucklin<;  the  ultimate  i)nll  of 


nice. 


the  rods,  they  will  have  ;i  very  clumsy  appear 

lion  of  a  cast-iron  washer  will  relieve  the  bendinj;  of  the  U,  but 

not  tiie  appearance:  besides,  it  is  better  not  to  introd 

iron  into  a  wrou,!;ht-iron  structure. 


he  inser- 


uce  cast- 


It 


IS  now  m  o 


filer  to  take  up  the  omitted  portions  of  Chap- 


ter IX. 

iMi-st,  to  find  the  number  and  distribution  of  the  rivets  in  the 
ilan-es  of  the  beam  there  designed,  let  us  divide  the  fifteen  feet 
between  centres  of  supports,  as  shown  in  the  accompanying 
diagram,  and  calculate  the  stresses  at  the  points  of  division. 


a'6" 


><     a'o"     )  <     a'o"     ><  i'o"> <  i'o"> <     I'a" 


2'f>'' 


The  ro-action  at  each  end  is  about  8.5  tons,  and  the  uniformly 
distributed  load  about  0.0044  ton  per  lineal  inch.  The  moment 
at  the  first  point  of  division  from  the  support  is 

8.5  X  30  -  0.0944  X  30  X  15  =  212.5  inch  tons. 

At  the  ne.\t  point  of  division  the  moment  is 

^^•5  X  54  -  0.0944  X  54  X  27=  3  21. 3  inch  tons, 

and  at  the  ne.xt  j)oint  it  is 

cS.5  X  7S  -  0.0944  X  7.S  X  39  --  3  75.,S  inch  tons. 


loS 


0A'/)/A:1  A'  1  •  /A'lKV  II lull  1 1  \1  i  -BAJlKiKS. 


From  the  last  equation  of  Appendix  II.  we  have  for  the  value 
of  the  flange  stress  at  any  section, 

M 


S  = 


In  this  case 


Dividing  each  of  the  moments  by  36.7  gives,  for  the  horizontal 
stresses  at  the  three  points  of  division,  respectively  5.8  tons. 
8.74  tons,  and  10.24  tons.  Therefore,  between  the  centre  of 
the  support  and  first  point  of  division,  there  must  be  enough 
rivets  to  take  up  a  horizontal  stress  of  5.8  tons;  between  the 
first  and  second  points,  enough  for  a  horizontal  stress  of 
8.74  —  5.8  =  2.94  tons;  and  between  the  second  and  third 
points,  enough  for  a  horizontal  stress  of  10.24  —  8.74=  1.5  tons. 

The  vertical  pressure  upon  the  rivets  of  the  upper  flange  is 
about  12  X  0.0944  =  1. 133  tons  per  lineal  foot,  making  the  total 
vertical  stresses  for  the  three  divisions  respectively  2.83  tons, 
2.27  tons,  and  2.27  tons.  Combining  these  by  the  ixirallelogram 
of  forces  with  the  horizontal  stresses  last  found,  gives  the  total 
stresses  for  each  division  6.45  tons,  3.71  tons,  and  2.72  tons 
respectively. 

From  Table  XXXVI.  we  find  the  resisting  bending-moment 
of  a  five-eighth  inch  rivet  to  be  0.18  inch  ton,  and  the  working 
bearing-pressure  on  a  quarter-inch  plate,  0.938  ton. 

Let  us  first  consider  the  stress  of  6.45  tons.  It  is  equally 
divided  between  the  two  angles,  making  the  stress  on  each  3.22 
tons.  The  lever  arm  of  this  last  stress  is  .](]  +  /l;)  =  aV'  ^"'^ 
the  moment  ^.i  X  3.22  =0.906  inch-ton,  dividing  which  by  0.18 
gives  five  as  the  number  of  rivets  required  to  resist  bencUng. 
Dividing  6.45  by  0.938  gives  seven  as  the  number  required  for 
bearing.  If  there  be  but  seven  rivets  in  two  feet  and  a  half, 
the  spacing  will  be  five  inches,  which  would  be  practically  too 
great.  It  is  better  to  space  the  rivets  two  and  a  half  inches  near 
the  ends  of  the  beam  ;  and,  if  it  be  thought  advisable,  the  distance 
may  be  increased  to  foiu"  or  even  five  inches  near  tlie  middle. 


ORDINARY  IRON  HIGHWAY- BRIDGES. 


109 


iMoni  the  above,  wo  may  conclude  that  calculating  riv?! 
.spacin.^;  for  flanges  of  floor  beams  is,  as  a  rule,  too  much  refme- 
iiunt  lor  highway-bridge  designing. 

If  the  depth  of  the  beam  W  reduced  near  the  ends,  or  if,  by 
reason  of  lack  of  headway  biMU-ath  the  1 


be  used,  it  might  be  well  to  -fu  tl 


iridge,  shallow  beariis 


Next  let  us  make  th 


irough  the  above  investi-at 


ion. 


le  design  for  a  trussed  floor  beam,  takin; 
a  twenty-foot  panel  and  a  tweiUy-funr  foot  roadway  of  a  brid'^i 

;jives    the  weight  of  ai 


belonging  to  Class  A.      Table    XIX 


ordi 


IK'I- 


nary  built  beam  for  these  dimen 


lineal  foot :  so  let 


sions  as  ninety-four  pounds 


us  assume  the  weight  of  the  trussed  1 


)eam 

to  be  eighty  pounds  per  foot,  also  the  length  of  beam  between 
centres  of  supports  to  be  twenty-five  feet.  The  live  load  will 
he 

24  X  20  X  100 
2000 

Table  XV.  gives  3339  as  the  number  of  feet  of  pine  lumber  per 
panel,  the  weight  of  which  is 


=  24  tons. 


3339  X  5 


2  X  2000 

and  the  weight  of  the  beam  itself  is 

26  X  80 


=  4.174  tons; 


2000 


=  1.04  tons; 


makmg  the  total  load  equal  to  29.214.  or  1.1686  tons  per  lineal 
f<)t)t.  Let  us  use  two  jwsts.  The  central  panel  should  be  ten 
feet  long,  and  each  of  the  others  seven  and  a  half  feet.  Let  us 
assume  the  beam  to  be  a  10"  30#  I,  and  the  depth  of  the  truss 
five  and  a  half  feet  centre  to  centre.     Then  in  the  formula 


3  4> 


we  will  have  iv  =  1.1686,  I,  =  10,  </  =  -f„  nearly,  C=  5,  P  = 
.]X  1. 1686  X  17.5  =  10.225,  /,  =  7.5,  r"^3,  D=s.S,  and  A' 
;d)out  8x032  =  2.56.  Substituting  these  values  gives  A  +  A" 
=  3  21  as  the  area  of  one  flange.  The  total  area  of  the  section 
would  then  be  2  X  321  +  2.56  =  8.98  square  inches,  which  cor- 
responds  altpost  exactly  with  the  area  of  a  thirty  pound  I-beam. 


h 


11  I  •  '  ( 


I 


pit 


ifliiri 


no 


OA'/>/X^IUy   /A'(>.\    JlhiJ/UA  \-JiRiniJKS. 


Tho  (k'si^n  for  llu-  post  agrees  with  that  shown  in  Fipj.  i6, 
riale  II.,  with  tlie  exception  that  the  end  (Uagonals  are  not 
adjustable.  The  stress  on  a  post  is  /' =  10.225  tons  ;  that  on 
the  bottom  cliord  is 

that  on  the  end  diaj^onals  is 

/>^i:cO—  10.225  X  1-69=  1 7.28  tons; 

that  on  the  counters  is 

j'\,/'sLr  «'  =  0.3  X  10.225  '^  2.16  =  6.625  tons. 

The  Mitensity  for  the  tension  menilK-rs  should  be  four  tons, 
making-  the  sections  required  for  tlie  chord  bars  and  main 
dtogonals  respectively  3.48  and  4.32  square  inches.  Referrin<; 
to  Carnegie's  "  rocket-Companion,"  p.  94,  we  find  that  two 
§"  X  2\"  bars  will  do  for  the  former,  and  two  \"  X  2^"  bars  for 
the  latter.  From  Table  IX.  we  find  that  two  one  and  a  quarter 
inch  rods  will  be  re(|uired  for  the  counters. 

To  the  stress  on  a  post  must  be  added  the  vertical  component 
of  the  initial  tension  on  the  counters,  which  is  about 

2  X  1.5  X  0.46  =  1.38  tons; 

making  the  total  stress  1 1.605.  Before  ajiplying  Table  XL.,  we 
must  multiply  this  stress  by  about  1.5,  the  ratio  of  the  factors 
of  safety  for  wind  bracing  and  floor-beam  struts;  making  the 
total  stress  17.407  tons.  Using  the  column  for  one  fi.\ed  and 
one  hinged  eiul,  we  find  that  a  6"  15*  I-beam  will  be  reciuired. 

To  find  the  thickness  of  the  pin  plate  at  the  end  of  the  beam, 
let  us  assume  it  at  five-eighths  of  an  inch  ;  then  the  lever  arm  of 
the  diagonal  stress  will  be  .1(5  +  5)  =  •]  inch,  and  the  moment. 

17  28 

3  X  -^" —  =  6.48  inch  tons. 

2 

Consulting  Table  XII.,  we  find  that  the  necessary  diameter  of 
pin  is  two  inches  and  an  eighth.  Referring  to  Table  XXVI., 
and  looking  down  the  column  for  a  two  and  an  eighth  inch  pin, 
we  find  that  the  necessary  bearing  will  be,  for  8.64  tons,  eleven- 
sixteenths  of  an  inch.  It  will  be  more  economical  to  increase 
the  diameter  of  the  pin  to  two  inches  and  three-eighths  than 
the  thickness  of  the  plate  to  eleven-sixteenths. 


OKD/XANV  /ROX  HIGHWAY-BRIDGES. 


\\\ 


rhths  than 


Next  let  us  find  the  number  of  rivets  necessary  to  attach  the 
plate  to  the  I  beam.  The  horizontal  and  vertical  components 
of  the  end  diagonal  stress  are  respectively 

17  28  X  0.8  =  13.82  tons 
and 

17  28  X  0.6=  10.37  tons. 
The  first  of  these  stresses  pioduces  bending;  and  the  second, 
direct  tension  on  the  rivets,     The  moment  of  the  first  stress  is 
about 

13..S2  X  J(!i  +  i')  =  9.5  inch  tons, 

uhirh.  divided  l)y  0.493,  tlie  resistiuf^-moment  for  a  seven-ei;;i,ths 
iiuii  rivet,  ioiind  in  Table  XXXVI.,  gives  twenty  as  the  nmnber 
oi  rivets  to  resist  bending.  To  resist  tension  the  number  re- 
quired will  be 

5  X  0.6  ~  *^' 

making  twenty-four  rivets  in  all  for  the  connection.  Seven- 
eighths  inch  rivets  are  rather  large  for  the  flanges  of  a  ten-inch 
beam,  as  there  is  not  room  for  full  heads  :  nevertheless,  it  is 
better  to  use  them,  on  account  of  the  increased  bending  resist- 
ance.. Using  twelve  rivets  on  a  side,  and  spacing  them  two 
inches  and  a  half  a])art,  will  make  the  length  of  the  plate  about 
thirty-two  inches.  It  is  evident  that  there  is  no  need  of  figuring 
for  bearing  in  this  connection. 

.\e.\t    let    us    proportion    the  connecting-plate  over  a   post, 
assuming  the  thickness  to  be  three-eighths  of  an  inch,  and  using 
live-eighths  inch  rivets.     The  moment  on  the  rivets  will  be 
1 1 .605  X  ,\  ( 3  +  ;. )  =  5  .oS  iii,:h  tons, 

which,  divided  by  o.  i.S  (the  resisting-moment  of  a  five-eighths 
inch  rivet),  gives  twenty-eight  as  the  number  of  rivets  required, 
or  fourteen  for  each  lug.  Using  staggered  rivets  spaced  two 
inchrs  apart  will  make  the  depth  of  each  lug  about  fifteen  inches. 
The  number  of  rivets  necessary  for  attaching  the  plate  to  the 
beam  is  partly  dependent  on  the  counter  stress,  and  partly  upon 
the  length  of  plate  which  we  consider  requisite  for  fi.xing  the 
cn.l  of  the  post.     About  eighteen   inches   ought  to  suffice  for 


»M{ 


112 


ORDIXARY  IROX  HICHWAV-BRIDGES. 


this  purpose.  The  horizontal  component  of  the  counter  stress, 
including  initial  tension,  is  9.625  X  0.89  =  8.566  tons,  and  its 
moment  on  the  rivets  is 

S  566  X  \{%  +  f )  =  4.82  inch  tons, 

which,  divided  by  0.31 1  (the  resisting-momcnt  for  a  three- 
fourths  inch  rivet),  gives  sixteen  as  the  number  of  rivets 
rec|uire(l.  Making  them  staggered,  and  spacing  them  two  and 
a  c|uarter  inches  apart,  would  make  the  length  of  plate  just 
twenty  inches. 

Let  us  assume  the  sections  of  the  re-enforcing  plates  at  the 
feet  of  the  posts  to  be  j,"  X  5";  then  the  lever  arm  for  the  cho'-d 
stress  will  be  ^(^  -|-  -J)  =  ^  inch,  and  that  for  the  vertical  com- 
l)onent  of  the  end  diagonal  stress  o(|  +  .}  +  V)  =  {o  ;  making 
the  horizontal  and  vertical  component  moments  on  the  pin 
respectively, 

.23  inch  tons 


13.044 


and 


10.225 


1(1 


4.79  inch  tons. 


The  resultant  moment  is 


V'(5.23)'+ (4.79)-=  7.09  inch  tons. 

It  is  evident,  that,  to  obtain  the  lever  arms  used,  the  chord  bars 
must  be  packed  on  the  outside  and  the  end  diagonals,  between 
the  chord  bars  and  the  post.  The  diameter  of  pin  correspond- 
ing to  7.09  inch  tons  is  2^';  but  a  2]"  pin  is  tlie  smallest  that 
can  be  used  with  a  2^"  bar.  The  post  l)earing  is  am|)le,  anil 
needs  no  testing. 

If  we  divide  the  bearing-stress  equally  between  the  post  and 
the  re-enforcing  plates,  there  will  come  upon  each  of  the  latter  a 
stress  of  2.9  ;  making  a  moment  upon  the  rivets  equal  to  \  X  2.9 
=  1.45  inch  tons,  which,  divided  by  o.  18,  gives  eight  as  the  num- 
ber of  five-eighths  inch  rivets  recjuired  for  each  plate.  Adding 
two  for  safety,  s])acing  the  rivets  two  inches  apart,  and  allowing 
room  for  the  eye-bar  heads,  will  make  the  length  of  each  re- 
enforcing  plate  about  si.xtcen  inches. 


ORDLVARY  IROX  nrGIIlVAV-nRIDGES.  ,,3 

The  moment  on  a  counter  pin  is  4.S1  x  i{ij  -f  U)  ^  3  ni  inch 
t..ns  corresponding  to  a  if"  pin.     %  examining  Table  XX\T 
■t  u-.ll  be  seen  that  a  2I"  pin  will  be  required  to  give  sufficient 


bcnnng 

.r 


Ke,errn,g  now  to  the  list  of  details  for  a  trussed  beam,  oivcn 
on  p.  30,  so  as  to  omit  nothmg,  we  can  make  out  the  bill  of  iron 
as  follows  :  — 


Uj)l'L'r  chord  beam 
l.oucr  clioid  bars  .     . 
I'^nd  diagonals   .     .     . 

Counters 

Posts 

Connecting.plates  .     . 
Ke-enforcing  plates     . 

i'in  jilates 

Stit'teners 

Tins 

I'ins 

Fins 

Fillers  ....".' 
Rivet  heads  ,     .     . 


Total  weight  of  beam 


4 

2 

4 


2 
4 


10" 

r' 
I" 

6" 

3'/ 

I" 

-5 

2-t" 
@ 


3o#I 

-4 

2i" 

O 

'5*1 

14" 

S" 
15" 

7  3#L 

O 

O 

Q 
2# 


26' 

780* 

■3' 

150" 

■3' 

379" 

IS' 

245  " 

5-3' 

159" 

3' 

105  " 

16" 

44'- 

32" 

167 '■ 

8" 

30' 

10" 

25- 

10" 

20'- 

13" 

29'- 

each 

8" 

about 

50- 

2, 191* 


1  hc'^  we>gln  of  a  plain    beam    for   the   same   place  would   be 
-0  X  94  -  3,444,  showing  a  saving  of  253  pounds  by  using  a 

mssed  beam  At  f^ve  cents  a  pound,  this  would  amount  to 
sM-.Os;  which  IS  considerably  more  than  the  cost  of  th- field 
nvct.ng,  and  extra  trouble  in  putting  such  a  beam  in  place  A 
-nnlar  investigation  for  a  trussed  beam  with  one  post  will  show 
"''^t  he  weight  of  such  a  beam  will  exceed  that  of  a  corre- 
sponding pkun  one:  so  there  would  be  no  economy  in  such  a 
ilcsign  for  this  case. 


1(1  >: 


III! 


i!  t 


114 


OKD/XAN 1  ■  IKOX  men  1 1 '.  /  )  -/iA'/DUhS. 


CHAPTER  XIV. 

BILLS   OF  MATERIALS,   AND   ESTIMATE   OF  COST. 

In  making  out  bills  of  materials,  the  list  of  members  given  in 
Chapter  III.  will  prove  of  great  assistance.  By  its  use,  one  can 
avoid  an  underci-,timatc  due  to  an  omission  of  any  of  the  parts 
of  the  structure.  A  good  way  to  make  out  a  bill  of  material 
is  to  prepare  si.\  vertical  columns,  in  the  first  of  which  write 
the  name  of  the  member  ;  in  the  second,  the  number  of  pieces  ; 
in  the  third  and  fourth,  the  dimensions  determining  their  sec- 
tion ;  in  the  fifth,  their  length  ;  and  in  the  sixth,  the  woiglit 
of  all  the  pieces,  or,  if  of  wood,  the  number  of  feet,  board  meas- 
ure, that  they  contain. 

The  following  examples  will  serve  to  explain  the  methotl  :  — 


DILL    OF    WROL'OIIT-IKOX. 


Chord  channels      .     .     . 

12 

7" 

10,1*  [ 

2,772# 

Batter-brace  channels     . 

8 

8" 

i2i#[ 

33''/' 

3.375  " 

Plate 

I 

X" 

4 

12" 

262' 

2,620  " 

Post  channels    .... 

8 

5" 

c>k#  c 

22^ 

1.144- 

Lateral  struts     .... 

4 

4" 

r*  c 

<5' 

360  •• 

Lateral  struts     .... 

4 

5" 

6.^#  [ 

•5' 

300  •• 

Main  {liai;onals.     .     .     . 

8 

r 

'T 

34' 

1.020" 

Counters 

8 

3" 
4 

3" 

35' 

5-5" 

Etc 

"" 

• 

" 

2.77-# 

3-375 '• 

2,620  " 

1.144  •• 

360  •• 

390" 

1.020  •■ 

5-5" 

ORDINARY  iRox  j//i;//ir.n--nA'/jH,j.:s. 

BILL    OK    LUMBKK. 


IIS 


Joists 


Flooring  .  .  , 
liand-rail  caps  . 
Handrail  posts. 
IJiil)  ])lanks  .  . 
1\11\-  planks .  . 
Lateral  struts     . 


55 

110 

20 

30 


4" 

14" 

3" 

12" 

2" 

6" 

4" 

6" 

2" 

12" 

6" 

6" 

8" 

8" 

'4' 
22' 

4' 

no' 

112' 

•4' 


Total  number  of  feet,  hoard  measure 


5/>47 
4,620 

440 
240 
440 
672 
224 


r  2,283 


It  IS  to  be  noticed  that  it  is  often  convenient,  as  in  the  case 
of  the  "Plate"  in  the  "Bill  of  VVroi.ght-Iron,"  or  that  of  the 
"IIuI,  planks"  in  the  "Bill  of  Lumber."  to  combine  several 
lcnt;ths  in  one. 

To  the  length  of  each  chord  bar.  main  diagonal,  and  hip  ver- 
tical  IS  to  be  added  three  feet  to  allow  for  the  weight  of  the 
licads  ;  and  to  that  of  each  adjustable  rod  about  five  feet  for 
the  heads,  upset  ends,  and  .sleeve  nuts  or  turn  buckles  Should 
greater  accuracy  be  required  for  the  weight  of  an  adjustable 
rod.  It  will  be  necessary  to  ascertain  what  length  will  be  needed 
at  each  end  for  the  heads,  and  how  much  for  the  upset  ends 
;'nd  adjusting-nuts  by  the  followin<' 

T.AHLI-    OF    EQUIVALENT    LEXGTMS    OF    RODS    FOR    UPSET   ENDS, 
NUT.S,    .SLEEVE    NUTS,    AND    TURN    BUCKLES. 


h'' 

-1" 

I  1  ' 

->r 

■iV 

—ill 

^" 

-2h" 

i" 

-4" 

I    6  " 

-2^ 

I  upset  end  and  i  nut 
I  upset  end  and  i  nut 
I  ujxset  i:\u\    and  i  nut 

1  U])set  end    and  i  nut 

2  u|)set  ends  and  r  sleeve  nut 

2  upset  ends  and  1  turn  buckle 


•i 

feet  of  rod 

'i 

feet  of  rod 

'f 

feet  of  rod 

'iV 

feet  of  rod 

1 
•3 

feet  of  rod 

3      feet  of  rod 


I  hcse  equivalent  lengths  do  not  include  the  lengths  of  the 
I'Psct  ends  themselves  :  they  represent  simply  the  e.vtra  lengths 
t"  be  added  to  the  bar  to  equalize  the  weight  of  the  nuts, 
slocve  nuts  or  turn  buckles,  and  the  e.xtra  iron  for  enlarging 
the  ends,  which  arc  six  or     '   " 


■  -I 

'  'I 


('i';lit  mcl 


loui 


ill 


ii6 


ORD/XARV  IROX  lIIGIIWAV-BRnyCES. 


It  is  not  necessary  in  a  preliminary  estimate  to  find  the  exact 
quantities  of  materials,  so  approximations  to  actual  dimensions 
can  be  made.     This  will  be  fully  illustrated  in  Chapter  XVI. 

Before  considering  a  bill  of  material  as  finished,  it  is  well 
to  look  it  over  to  sec  that  no  mistake  has  been  made  in  the 
number  of  the  pieces.  It  is  not  an  uncommon  error  to  put 
down  only  half  the  correct  number. 

As  soon  as  the  bills  of  iron  and  lumber  are  made  out  and 
checked,  the  dead  load  per  foot  should  be  calculated,  to  see 
if  it  agree  with  the  one  assumed  within  the  limit  specified  on 
p.  6. 

Estimates  of  cost  should  be  liberal ;  for,  as  a  rule,  the  actual 
profits  on  bridges  fall  short  of  the  amounts  estimated.  They 
can  be  made  very  readily  by  using  a  blank  similar  to  the  fol- 
lowing :  — 

Estimate  on Brittgc  across 


Lotiith  spoilt ft.    Ilcli^ht, ft.    Clear  Roadwayy ft. 

.Static  Load  per  lineal  ft., lbs.     Afoiuiii^  Load  per  lineal 

ft.,  Ids.     A'o.  Panels. Loigth  Panels.         ft. 

:      I         Cts. 

@ 

% 

© 

@ 

loads  (o 


II  'roiis^ht-iron.  lbs. 
Casl-iron,  lbs. 

Lumber,  ft. 

Piles,  ft. 

Hauling,        

Freight 

Framing 

Falsework 

Erection 

Spikes 

J'aintiri; 

Blacksinitliing 

Coal 

Freight  on  tools 

Travelling  expenses .... 
Men^s  time  travelling  .     .     . 

Bidding  expenses 

Teaming  during  construction 
Incidentals 

Total  cost  of  bridge    .     .     . 

Cost  per  lineal  foot    .    .    . 


ORDIXARV  IROX  HfGHVVAY-nRinarCS. 


117 


On  fair  country  road.s,  a  load  for  a  team  of  horses  may  be 
taken  to  be  a  ton  and  a  half  of  iron,  a  thousand  feet  of  pine 
lumber,  or  si.\  hundred  feet  of  oak  lumber. 

The  designing  of  falsework  will  be  treated  in  Chapter  XX. 
Its  cost  will  include  that  of  the  piles  in  place,  if  any  be  required! 
and  that  of  the  lumber,  to  which  should  be  added  about  three 
dollars  ])er  thou.sand  for  framing  and  raising,  and  a  dollar  or 
more  per  thousand  for  taking  down.  Falsework  timber  can 
generally  be  sold  for  something  when  the  bridge  is  completed  : 
so  a  reduction  may  be  made  in  its  cost  when  the  estimate  is  to 
be  a  close  one. 

The  cost  of  erection  can  be  found  approximately  for  ordinary 
conditions  from  Table  XXXVIII.,  by  multiplying  the  number 
of  days'  labor  there  given  by  the  average  rate  of  wages  for  ordi- 
nary bridge  hands.  It  must  not  be  forgotten  that  there  is  a 
great  variation  in  the  cost  of  erection  ;  for  it  depends  upon  the 
locality,  weather,  skill  of  laborers,  efficiency  of  foreman,  etc. 
Those  who  feel  inclined  to  question  the  correctness  of  this 
table  should  make  some  allowance  for  the  difficulty  which  the 
author  has  experienced  in  getting  any  data  whatsoever  upon 
the  subject.  Few  bridge  engineers  care  to  part  with  the 
knowledge  which  has  cost  them  both  time  and  money 

\\^  regard  to  cost  of  painting,  the  same  difficulty  has  been 
encountered  :  so,  for  lack  of  more  accurate  data,  the  followino- 
table  will  have  to  suffice.  It  has  been  prepared  from  a  few 
figures  of  co^,t  of  painting,  obtained  at  a  time  when  wages  were 
a  dollar  and  a  half  a  day. 


SrAN 

12'  roadw.iy. 

16'  ro.idw.iy 

20'  roadway. 

50' 

S6.0O 

?7  00 

8(9.00 

100' 

22.00 

25.00 

2S.OO 

150' 

- 

45.00 

51.00 

200' 
-50' 
300' 

- 

So.oo 
125.00 

90.00 
140.00 

1  70.00 

24'  roadway 


$11.00 
31  00 

57.00 
lOO.CO 

155.00 

1 90.00 


IV'lore  making  an  estimate  on  a  bridge,  one  should  endeavor 
to  ohtam  as  many  as  possible  of  the  followin<^ 


i       ^i'  B  V'.  t- 


lit 


Il8 


Oh'n/\AA'\'  /AOx  ///<;// 11. n-/,'A7/)(;/-:s. 


DATA   I'OK    OESIGNMNG    IRON    IIK.IIWAV  liKIOGE    SUPERSTRUCTURES, 
AND    I-.sri  MATING    THEIR    COST. 

Class  of  bridge  required. 

Length  of  span  or  spans. 

Width  of  clear  roadway. 

Headway  required  in  clear  above  floor. 

Live  load,  if  different  from  the  ordinary. 

Wind  pressure  per  square  foot,  if  different  from  the  ordinary. 

Any  extraordinary  load,  such  as  paved  flooring,  heavy  falls  of 
snow,  etc. 

The  velocity  of  passing  loads. 

Distance  of  bridge  site  from  nearest  railway-station  or  sea- 
port. 

Quality  and  condition  of  the  roads  between  these  places. 

Nature  of  bed  of  river,  and  velocity  of  stream. 

Height  of  lower  chord  above  bed  of  river. 

Cross  section  of  stream  at  crossing,  showing  borings,  if  any 
have  been  made 

Angle  which  the  direction  of  bridge  makes  with  axes  of  piers 
or  abutments. 

Nature  of  the  country  at  the  site. 

Any  special  difficulty  that  may  be  anticipated  for  the  raising. 

Kind  of  falsework  it  would  be  advisable  to  use. 

Cost  of  piles  at  various  places  in  the  neighborhood,  if  any  be 
required. 

Cost  of  transport  of  same  to  site. 

Cost  of  timber  per  thousand  for  falsework. 

Probable  value  of  falsework  timber  after  bridge  is  finished. 

Cost  of  withdrawing  piles,  if  necessary. 

Number  of  lineal  feet  of  piles  recjuired. 

Number  of  feet  of  lumber  for  falsework. 

Cost  of  spikes,  bolts,  and  nails  for  falsework. 

Cost  of  driving  piles. 

Cost  of  transporting  pile-driver  to  and  from  site. 

Common  laborer's  wages. 

Skilled  laborer's  wages. 

Foreman's  wages. 

Wages  for  team  and  teamster. 


ONn/X.lKV  IKOX  HIGHWAV-nRlDGES. 


RUCTURES, 


119 


Cost  of  siipcrintcrclcncu  by  cnt^incer  or  engineers. 

Number  of  days'  teaming  on  work. 

Date  when  bridge  must  be  finished. 

I'robable  length  of  time  it  will  take  to  raise  and  complete 

)ri(lge. 

Chances  of  fair  or  foul  weather  during  this  time. 

Chances  of  having  falsework  carried  away  by  a  sudden  rise  or 


in  icc-gorge. 


Chances  of  a  scarcity  of  laborers. 

Chances  of  sickness  among  laborers. 

Expenses  attendant  on  same. 

Cost  of  tents  or  other  housing  for  laborers,  if  any. 

Cost  of  iron  at  mill  or  foundry. 

Cost  of  transport  of  same  to  nearest  railway-station  or  sea- 
port. 

Cost  of  lumber  per  thousand  at  mill  or  market. 

Cost  of  transport  of  same  to  nearest  railway-station  or  sea- 
port. 

I'robable  expenses  for  blacksmithing  and  coal. 
Cost  of  tools,  if  it  be  necessary  to  buy  .special  ones. 
Wear  and  tear  of  plant,  and  loss  of  tools. 
Loss  of  bolts  and  timber. 

Actual  cost  of  raising  similar  structures  under  similar  circum- 
stances. 

Trax-elling  expenses  of  employees  to  and  from  site, 
lidding  expenses,  if  any. 
Office  expenses  in  preparing  plans,  etc.* 
Advisable  allowance  for  contingencies. 


»  Tlus  is  „su.,lly  not  considered,  as  it  is  a  constant  e.xpense,  and  comes  out  of  t!,e  aiini.al 
gross  i]rolUs  ot  the  company. 


120 


ORDLVAKV  IKO.y  H hi U WAY-BRIDGES. 


CHAPTER  XV. 


ECONOMY. 


The  first  point  to  be  considered,  when  dccidinj:^  upon  the 
style  of"  bridge  for  a  certain  stream  crossing,  is  the  ninnber  ol 
spans.  It  is,  in  reality,  a  consideration  of  economy  wliich 
determines  this  ;  for  the  best  bridge  to  l)uild,  provided  that  the 
water-way  be  not  too  much  contracted,  is  the  one  for  whicli 
the  sum  of  the  cost  of  superstructure  and  the  cost  of  founda- 
tions is  a  minimum.  If  the  water-way  be  too  much  interrupted, 
the  design  would  not  be  an  economical  one,  even  if  its  first  cost 
were  the  least,  because  of  the  risk  of  washout  to  which  the 
bridge  would  always  be  subject. 

In  most  cases,  there  is  not  much  choice  concerning  the  num- 
ber of  spans,  local  considerations  often  determining  it ;  but  there 
is  occasionally  a  choice  between  two  or  even  three  numbers. 
The  only  way,  then,  to  decide  is  to  make  a  rough  estimate  of  the 
cost  of  the  superstructure  and  the  foundations  for  each  number; 
then,  if  the  choice  fall  about  equally  between  two  numbers,  it  is 
better  nearly  always  to  adopt  the  longer  spans,  because  the 
actual  expense  for  the  foundations  usually  exceeds  the  amount 
of  the  preliminary  estimate. 

Another  preliminary  point  to  be  settled  is  whether  it  would 
be  most  economical  to  build  an  iron,  a  combination,  or  a  wooileii 
bridge.  Although  this  work  treats  of  iron  bridges  only,  still 
this  is  a  point  which  ought  to  be  considered. 

The  following  mathematical  treatment  of  the  problem  was 
given  by  the  late  Ashbel  Welsh,  C.lv,  past  president  of  the 
American  Society  of  Civil  Engineers  :  — 


rv.v>A\-./  -J-  /Rox  iiiGnWAv-nR/ncEs 


121 


1"  MM'  llIK  (CMPAKA-nvK  r.CONOMV  OF  TWO  HRIDOKS  OF  niF- 
I  KKF.NT  COST  AND  I.UKAMIMTV,  THAT  Wir.L  A.NSWKK  TMKSAME 
I'lKPOSK    KOUALLV    WELL    WHILE    TllEV    LAST 

'  Lot  The  the  cost  and  assumed  real  value  of  one  of  them   T 
the  time  it  will  last,  a  the  compound  interest  on  one  dollar 'for 
that  tune,  at  whatever  rate  money  is  worth  to  the  party  paying- 
for  the  hndge,  and  /.  the  loss  on  the  bridoe  at  the  end  of  the 
lime  T,  or  the  amount  which  it  would  take  to  make  it  as  -ood 
as  new.    Let  A'  be  the  real  value  of  the  other  bridge,  C  its  cost, 
/    lis  duration,  n'  the  compound  interest  on  one  dollar  for  that 
lime,  and  /.'  the  loss  on  the  bridge  at  the  end  of  the  time  V 
or  the  amount  required  to  make  it  as  good  as  new.    And  let  Tbc 
I  he  real  value  of  the  bridge  that  would  last  forever  if  all  cir- 
cumstances should  remain  constant. 

'  Xow.  supposing  that  the  money  required  for  building  had 
been  borrowed  for  an  indefinite  time,  the  actual  expense  at  the 
end  of  the  time  T  to  the  party  paying  for  the  bridge  which 
would  last  forever  would  be  aV;  and  the  actual  expense  at  the 
ciul  of  the  same  time  for  the  first  bridge,  after  making  it  as 
^ood  as  new.  would  be  aC  ^  L.  These  two  quantities  are 
equal  :  therefore  the  hitherto  unknown  value  of  V\^ 


C4- 


Z 
a 


S.mlIal■l>^  at  the  end  of  the  time  T\  the  expense  for  the 
bridge  which  xvould  last  forever  would  be  a'V;  and  that  for 
the  second  bridge,  after  making  it  as  good  as  new,  if  the  cost 
luul  been  the  real  value  R,  would  be  a' R  +  L' .  As  before,  these 
iwo  values  are  equal;  and  therefore, 

T' 

V=R^^j. 
a 


I'iquating  the  two  values  of  V  gives 


and 


R=C  +~-^. 
a       a' 


1,1-! 


12: 


ORDI  C  \RV   IROX  IIICIIW \IY  -H RIDGES. 


Now,  if  the  value  thus  found  for  R  be  greater  than  the  cost  C\ 
the  second  l)ridi;e  is  more  economical  than  the  fust ;  while,  if  it 
be  less,  the  first  bridge  will  be  the  more  economical.' 

The  next  economic  consideration  is  that  of  depth  of  truss. 
Upon  this  subject  much  has  been  written,  and  many  investiga- 
tions have  been  made;  the  general  conclusion  being,  that  the 
depth  should  be  from  one-seventh  to  one  tenth  of  the  span  : 
some  ICnglish  writers  say  from  one  tenth  to  one-fourteenth  of 
the  span  ;  while  only  one,  as  far  as  the  author  knows,  —  Benja- 
min r.aker,  C.l':.,  in  his  treatise  on  "Beams,  Columns,  and 
Arches,"  —  makes  it  from  one  fifth  to  one-seventh  of  the  si)an. 

Such  investigations  being  purely  mathematical,  and  involving 
the  use  of  the  differential  calculus,  are  of  little  practical  value, 
as  they  cannot  take  into  account  the  numerous  variables  that 
ought  to  be  considered.  Not  only  do  the  stresses  in  a  truss 
vary  with  the  depth,  but  also  the  intensities  of  working-stress 
in  the  compression  members.  These,  again,  vary  with  the 
number  of  panels  ;  and  this  variation  is  according  to  a  law  or 
laws  altogether  too  complicated  to  be  handled  by  the  calculus. 
Again  :  the  intensity  of  working-stress  varies,  or  should  vary, 
according  to  the  position  and  importance  of  the  member. 

In  view  of  the  complexity  of  the  question,  and  wishing  to 
determine  the  most  economic  depths  for  Pratt  and  Whipple 
trusses,  the  author,  about  a  year  ago,  undertook  to  solve  the 
problem  in  a  practical  manner  by  assuming  the  most  common 
clear  roadway  (sixteen  feet),  and  figuring  out  a  number  of  dia 
grams  of  stresses,  and  bills  of  materials.  At  first  he  considered 
that  It  would  be  necessary  to  calculate  the  total  actual  cost 
for  every  case,  but  upon  further  investigation  found  that  il 
would  be  sufificient  to  figure  out  the  sections  and  weights  per 
lineal  foot  of  the  different  members  of  one  truss,  multiply  these 
by  their  respective  lengths,  and  sum  up  the  products,  neglect- 
ing all  consideration  of  details,  because  the  differences  in  the 
weights  of  the  latter  balance  each  other.  Thus,  if  the  depth  of 
a  truss  be  increased  by  one  foot,  there  would  be  a  little  increase 
in  the  weights  of  the  lattice  bars  and  rivets  and  a  decrease  in 
,  that  of  the  pins  anil  eye-bar  heads.  These  may  be  taken  as 
balancing  each  other,  without  making  any  appreciable  error. 


rMvv.\- //>•)■  //cnx  nir.mr.w-nRiin-.F.s.  ,23 

TiK-  im.sl  economic  Icn-tli  of  pand  was  at   tlic  same  tinic 

.nvcst,K.itc-cl,  and  was  determined,  witl,ni,t  preparing;  complete 

hills   of  materials,   by  co.isiderin^^  only  those   portions  of  the 

structure  wiiich  are  affected  by  the  variation  in  the  number  of 
panels. 

Economy  in  pony  trusses  is  an  element  which  ou^ht  seldom 
t(.  influence  the  design,  for  a  good  bridge  of  this  kind  will  .re„. 
erally  reqiure  more  iron  than  the  ordinary  calculations  demand 
instead  of  trying  to  avoid  a  little  expense,  regard  should  be 
paid  to  obtaui.ng  a  good  distribution  of  plenty  of  material  in 
Older  to  partly  compensate  for  the  lack  of  rigidity  which'  is 
characteristic  of  the  pony  truss.  In  very  wide  pony-truss 
hrulgcs,  especially  when  the  length  of  span  approaches  its 
superior  economic  limit,  it  might  be  well  to  make  a  few  calcula- 
tions concerning  the  economic  depth;  but  the  number  of  panels 
shou  d  be  regulated  by  the  slope  of  the   batter  braces,  which 

should  never  be  less  than  two  and  a  quarter  horizontal  to  one 
\crtical. 

The  superior  economic  limit  of  the  pony  truss  is  not  a  fi.xcd 
quantity,  but  decrea.ses  as  the  width  of  the  bridge  and  the  load 
mcrease,  and  as  the  intensities  of  working  stresses  diminish 
l;..r  example,  comparing  a  pony  tru.ss  and  a  thn.ugh  brid-e  of 
sixty.five  feet  span  in  four  panels,  sixteen  feet   clear  roadway, 
designed  according  to  Class  C,  there  is  found  a  difference  of 
three  hundred  pounds  of  iron  in  favor  of  the  pony  truss  ;  while 
w'th  the  same  span,  for  a  twenty-foot  clear  roadway,  and  bridge 
designed  according  to  Class  A,  there  is  a  difference  of  eleven 
nindred  and  fifty  pounds  of  iron  in  favor  of  the  through  brid-e 
I'..r  a  clear  roadway  of  twelve  feet,  the  superior  economic  limit 
of  the  pony  truss  would  reach  as  high  as  seventy-five  feet  ;  and. 
m-  very  wide  bridges,  the  inferior  economic  limit  of  the  throuoh 
bn'lge  would  reach  as  low  as  fifty-five  feet  :  but,  on  account^of 
>  ■guilty,  the  superior  limit  of  the  former  may  be  placed  at  sixty- 
^ve  teet  ;  and,  on  account  of  appearance,  the  inferior  limit  of  the 
latter  at  the  same  length. 

After  making  out  diagrams  of  stresses,  and  bills  of  materials 
'"'•"ver  one  hundred  spans,  the  author  came  to  the  followin-^ 
conclusions  :  —  =" 


i     I 


124 


(>A'/>/.\.!/:)'  j/:(i.\  I  Hi,  1 1  WW  v-i',RiiH,i:s, 


n\ 


I  till  ^' 


That  if  ttu'  economic  depth  he  calcuhitod  for  any  span,  where 
the  panel  length  is  twenty  feet,  or  the  nearest  leni^th  helovv 
twenty  foet,  and  if  the  economic  depth  for  the  same  span,  l)ut 
with  one  panel  less,  be  calculated,  the  latter  will  exceed  the 
former  by  one  or  two  feet. 

That,  in  places  where  lumber  is  expensive,  it  will  not  be  well 
to  make  panels  over  twenty  feet  lonj^,  or,  in  places  where  it  is 
cheap,  to  make  them  over  twenty-four  feet  lonj;,  because  tim- 
bers exceeding  tiie  latter  lenj;th  are  not  easily  procured.  Then, 
too.  iji  designin<;  iron  brid<,'es,  which  are  supposed  to  last  indeli- 
nitelv,  it  must  be  remembered,  that,  as  time  j^^oes  on,  loni;- 
timbers  will  become  more  and  more  expensive,  and  less  easily 
procurable,  even  in  timber  districts ;  so  that  panels  exceeding- 
twenty  feet  in  length  should  be  employed  very  cautiously. 

For  appearance,  through  spans  of  one  hundred  feet  and  under 
should  have  five  panels. 

The  principal  objections  to  the  use  of  the  double  intersection 
for  short  spans  are,  that,  as  the  rods  are  long  and  slender,  they 
will  vibrate  more  than  the  shorter  and  larger  ones  of  the  single 
intersection.  Any  flaw  in  a  small  rod  will  have  a  proportion- 
ately greater  injurious  effect  than  the  same  sized  flaw  in  a  larger 
rod.  Long  and  slender  rods  are  difficult  to  transport,  and  arc 
liable  to  become  twisted  and  bent ;  though  this  objection  can 
be  partially  removed  by  halving  them,  and,  as  the  posts  are 
light,  they  will  spring  more  under  the  shock  of  rapidly  moving 
loads. 

As  the  width  of  roadway  and  the  live  load  increase,  and  as 
the  intensities  of  working-stresses  diminish,  the  inferior  limit 
of  the  double  intersection  may  be  lowered.  The  table  on  p.  8 
{rives  the  limits  which  the  author  would  recommend. 

The  common  idea  among  highway-bridge  builders,  that  a 
double-intersection  bridge  should,  for  economy's  sake,  have  more 
panels  than  a  single-intersection  bridge  of  the  same  span  and 
loading,  is  incorrect. 

The  economic  depth  for  a  double-intersection  truss  is  about 
three  feet  greater  than  that  for  a  single-intersection  truss  of 
the  same  span,  and  number  of  panels. 

Tables  IV.  and  V.  give  the  principal   results  of  the  before- 


oA'/'/.v.iAT  /AiKv  ///(/// ir. I  r-/!Av/)(:/-:s\ 


I2« 


nu'.itioncd  iiuvsti-ati<.ns.  The  first  is  the  ..nc-  to  he  (M-(lin:.nly 
iise.l  :  the  .see<-ii<I  may  he  em|)I()ye(l  for  districts  where  the  tiiii- 
her  is  hirj^e  and  plentiful. 

There  seems  to  he  an  iinf..unded  prejudice  in  the  minds  of 
cnimiy  commissioners  and  hrid-e  sui)ervisors  a-ainst  Ion-  pan- 
els.  Practically  they  make  a  hetter  brid-c  than  do  short  panels  ; 
for  tlie  members  are  fewer  and  lar-er,  and  therefore  less  affected' 
by  Haws,  besides  less  subject  to  vibration,  and  less  hable  to 
maccuracy  of  construction.  The  floor  beams  and  joists  bein- 
lar-er.  there  is  less  probability  of  often  receivin-  their  ma.xinum" 
workin-.loads.  The  only  real  objection  to  Ion-  panels  is  the 
extra  cost  of  the  joist  timbers  when  they  arc  to  be  replaced. 

In  addition  to  what  precedes,  the  following  general  economic 
considerations  should  always  receive  attention. 

Field  riveting  should  be  avoided  as  much  as  possible,  and 
designs  should  be  made  so  that  all  the  parts  will  come  to-ether 
readily  during  erection.  '' 

Kivets  should  be  spaced  with  regularity,  .so  as  to  facilitate 
tile  i)unching  of  the  holes  by  riveting  machines. 

it  is  generally  better,  in  through  'bridges,  to  pack  all  but  the 
end  chord  bars  outside  of  the  posts,  and  reduce  the  width  of 
top  chord  plate  to  a  minimum. 

It  is  not  always  better  to  employ  the  apparently  most  economi- 
cal depth  of  channels.  For  instanc  .  if  there  be  a  choice  of 
using  ten  or  twelve  inch  channels  for  the  top  chords  and  batter 
braces,  and  if  the  S(rf/(»/s  alone  would  indicate  a  saving  of  sav 
three  hundred  pounds  of  iron  by  the  use  of  the  twelve-inch 
channels,  the  others  would  be  more  economical  ;  for  the  twelve- 
inch  channels  require  larger  stay  plates,  lattice  bars,  and 
re-enf„rcing  plates,  besides  a  wider  top  chord  plate,  which  would 
increase  the  weights  of  the  cover  plates,  chord  pins,  post  lat- 
ticing, post  stay  plates,  shoe  plates,  etc.,  and  even  add  a  little 
to  the  lengths  of  the  floor  beams. 


the  beforc- 


1^ 


' 


ilH^i 


126 


ORDLXARY  IROX  HIGHWAY-BRIDGES. 


w 


, 


1r* 


CHAPTER   XVI. 

COMPLETE  DESIGN  FOR  A  BRIDGE. 

Let  the  bridge  to  be  designed  have  a  span  of  one  hundred 
and  sixty  feet,  and  a  clear  roadway  of  fourteen  feet  with  no 
sidewalks,  and  let  it  belong  to  Class  A.  Referring  to  the  table 
on  p.  8,  we  see  that  the  trusses  should  be  of  single  intersec- 
tion. On  p.  5  we  find  that  the  live  load  should  be  eighty 
pounds  per  square  foot  of  floor,  which  corresponds  to  eleven 
hundred  and  twenty  pounds  per  lineal  foot  of  bridge. 

Table  I.  gives  the  dead  load  as  seven  hundred  and  forty-two 
pounds  per  lineal  foot,  say  seven  hundred  and  forty  pounds. 

Table  IV.  gives  eight  for  the  number  of  panels,  and  twenty- 
four  feet  for  the  economic  depth. 

The  diagonal  upon  20  and  24  is  31.24,  which  divided  by  24 
gives  1.3  for  the  secant ;  and  20  divided  by  24  gives  0.833  for 
the  tangent. 

The  panel  live  load,  ic,  is  equal  to 

1 1 20  X  20  .  ^ 

1  y^ =  C.6  tons. 

2000 

The  panel  dead  load,  \\\,  is  equal  to 

740  X  20 


2000 


=  3.7  tons. 


Let  us  assume  that  about  a  third  of  this  is  concentrated  at 
the  upper  panel  point,  making 

W  =  1.2  tons. 

The  sum  of  the  live  and  dead  panel  loads,  or  W",  is 

5.6  4-  3.7  =  9.3  tons. 


2ntratcd  at 


OlWrNARY  IRON  HIGHIVAV-BRIDGES.  127 

One-eighth  of  zc  is  0.7  ton,  which  multiplied    by  i  x   dves 
0.91  ton.  ^     '^  ^ 

The  panel  dead  load  multiplied  by  the  secant  is 
3.7  X  1.3  =  4.81  tons. 
//'"  multiplied  by  the  tangent  is 

9-2>  X  0.833  =  7-747  tons. 
The  following  table  of  data  can  now  be  written  :  — 


'to 

«  =    8 
/=  20 

«'=  24 

diag.  =  31.24 

sec  0  =    1.3 

tan  6  =    0.833 

71'  =     5.6 

^^.=    3-7 
ilV,=    1.85 


ir  =  1.2 

iw  =  0.7 

iw  sec  (9  =  0.91 

^j  sec  6  =  4.81 

^IV^  sec  (9  =  2.405 

IV"  tan  ^  =  7.747 

^  IF"  tan  6=  3.873 


Next  let  us  draw  the  skeleton  diagram  shown  on  Plate  V 
and  number  the  panel  points,  commencing  with  zero  at  the  right! 
liaiul  end.  ^ 

First  let  us  find  the  stresses  in  the  diagonals,  using  Table  XLI 
1  he  stress  in  the  counter  at  the  point  2  is 

-Pc  sec  e  -  |/F,  sec  ^  =  3  X  0.91  -  3  X  2.405, 

a  negative  quantity,  which  shows  that  there  is  no  stress  on  this 
member.     Let  us  mark  it  zero  on  the  diagram. 
The  stress  in  the  couiter  at  the  point  3  is 

f«.  sec  6  -  A  ^//  sec  6  =  6  x  0.91  -  2.405  =  3.055. 

Fct  us  mark  this  and  all  succeeding  stresses  on  the  diagram 
1  he  stress  m  the  main  diagonal  at  the  point  4  is 

V^^  sec  e  +  ^  IV,  sec  ^  =  ,0  X  0.91  +  2.405  =  1 1.505. 
That  in  the  ne.\t  main  diagonal  is 
V^  sec  6  +  UV,  sec  fl  =  .5  x  0.91  +  3  X  2.405  =  20.865. 


128 


ORD/X.IR]-  /A'OX   IinUlU'A  Y-BRIDuES. 


That  in  the  ciul  main  cliaironal  is 


2i7i'  sec  0  +  •!//',  sec  U 


!i   X  0.91  4-  5  X  2.405  =  31.135. 


That  in  the  hatter  hrace  is 


28 


7i'  sec  ti  -\-  \  /Fj  sec  ^  =  28  x  0.91  +  7  X  2.405  —  42.315. 


That  in  the  middle  post  is 

I,,,  _  iJFi  +  W  =  6  X  0.7  -  1.85  +  1.2  =  3.55- 

That  in  the  next  post  is 


JLQ 


w  +  \  \]\  +  /r  =  10  X  0.7  +  1.85  + 


1.2  =  10. oc 


That  in  the  next  is 

^§w  +  •;!  \V,  4-  W  =  15  X  0.7  +  3  X  1.85  +  1.2  =  17.25. 

The  stress  in  the  top  ehord  at  the  panel  next  to  the  centre  is 

1 

IW"  y^^\-  {Y  +  2  +  3)  W"-^  =  SIF"  tan  6  =  61.976. 
a  II 

That  in  the  next  panel  is 

(8  -  i)  IF"  tan  6  =  ji IV"  tan  6  =  58.103. 

That  in  the  next  is 

(72  -  Is)  ^^"'  tan  e  =  6/F"  tan  6  =  46.482. 

That  in  the  lower  chord  at  the  panel  next  to  the  centre  is  the 
same  numerically  as  that  in  the  top  ehord  at  the  second  panel 
from  the  centre  ;  viz.,  — 

7UF"  tan  ^=  58.103. 

Similarly,  that  in  the  next  panel  of  the  lower  chord  is 
6  TF"  tan  6-- 46.482. 

That  in  the  remaining:  panels  is 

(6  -  2?,)  ;F"  tan  0  ^  3.I  IV"  tan  6  =  27.114. 


0/^J)/X.lRV  //Uh\   HIGHll-AV-BRinC.ES. 


129 


A  check  by  moments  about  the  hip  gives  the  stress  in  the 
lower  chord  at  the  end  panel  3.] //'"  tan  ^.  which  shows  that 
the  chord  stresses  are  all  right. 

Next  let  us  determine  if  any  stiffening  be  required  in  the 
end  panels. 

An  examination  of  Table  XXV.  sh<.ws  that  the  diameter  of 
the  end  lower  lateral  rod  is  one  and  eleven-sixteenths  inches 
Consulting  Table  IX.,  we  find  that  the  greatest  working-stress 
that  can  ever  come  upon  such  a  rod,  including  the  initial  ten- 

,sion,  is 

I4.399  +  2.375  =  16.774  teas. 

The  cosine  of  the  angle  which  the  rod  makes  with  the  planes 
of  the  trusses  is  about  0.8  :  therefore  the  component  of  its  stress 
\\\  the  direction  of  the  chord  is 

16.774  X  o.S  =  13.419. 

Referring  to  Appendix  I.,  we  see  that  it  will  be  necessary  to 
assume  values  for  A,h,  and  r,  in  order  to  find  the  reduced  dead 
load  n .,  trom  previous  experience  these  values  may  be  taken 
as  follows  :  A,  =  10,  //  =  9,  and  .  =  1,  making 

"^■2  —  370  —  =  190  pounds. 

The  reduced  panel  dead  load  will  therefore  be 

190  X  20 


2000 


=  1.9  tons, 


and  the  stress  on  the  end  panel  of  the  windward  lower  chord 
when  the  structure  is  subjected  to  a  wind  pressure  of  thirty 
I'ounds  per  square  foot  of  surface,  will  be 

3hlV,  tan  O  =  lxi.ox  0.833  =  5.54  tons, 

showing  that  stiffening  is  decidedly  needed.  This  result  could 
lavc  been  predicted  with  certainty  from  what  was  stated  in 
<■  h;i[)ter  IV.  concerning  Table  I. 

Xcxt  let  us  find  the  sections  required  for  the  tension  mem- 

iHTS. 


1 30  OKDI.XA  A'  J  ■  /A'(  '-\'  11  hill  W A  J  -  BRIPGES. 

Dividing  the  stress  in  the  counter  at  the  point  3  by  2  gives 
1.528;  then,  looking  down  the  cohinin  marked  "Intensity  of 
Working-stress  =  4  tons,"  we  find  the  nearest  number  to  be 
the  one  corresponding  to  a  diameter  of  seven-eighths  of  an  inch  : 
so  wc  will  use  two  seven-eighth  inch  rods  for  this  place.  In 
reality  there  is  no  counter  needed  in  the  third  panel ;  but  it  will 
be  as  well  to  use  a  single  three-quarter  inch  rod  there  to  aid  in 
adjusting  the  trusses,  and  to  take  up  the  shock  of  passing  loads. 

The  intensities  of  working-stress  for  the  main  diagonal  are 
4i^,  4|,  and  5  tons.  Dividing  these  into  the  respective  stresses, 
we  find  the  sections  required  as  marked  on  the  diagram. 

As  the  lower  chords  at  the  first  and  second  panels  are  to  be 
stiffened,  the  intensity  of  working-stress  for  the  inner  bars  at 
these  places  will  be  4  tons  :  the  intensity  for  the  rest  of  the 
chords  will  be  5  tons.  Dividing  these  intensities  into  the 
stresses  will  give  the  sections  required,  which  are  marked  on 
the  diagram.  The  section  for  the  first  and  second  panels  was 
obtained  by  supposing  that  there  are  four  bars  of  equal  size 
used  there  ;  so  that  the  average  intensity  is  4.]  tons. 

These  two  trussed  bars  of  the  end  panel  will  not  be  strong 
enough  to  resist  the  difference  between  the  C()ni|)ressive  stress 
of  13.42  tons  and  the  tensile  stress  of  5  54  tons  or  7.88  tons:  so 
we  will  have  to  use  an  I-beam  between  them,  the  trussing-bars 
being  attached  to  tiie  web.  This  is  a  more  economical  arrange- 
ment than  two  channels  laced  or  latticed.  Let  us  try  a  4"  I. 
Consulting  Table  XL.,  we  see  that  for  two  round  ends  the 
strength  of  a  4"  10*  I  is  5  tons,  because  it  is  held  by  the  truss- 
ing from  lateral  deflection.  Sul)tracting  this  from  7.88  leaves 
2.88  tons  to  be  resisted  by  the  two  bars,  or  0.88  ton  per  square 
inch,  which  {vide  Table  XI.)  is  by  no  means  excessive. 

The  stress  in  the  top  chord   is  probably  so  great  that   the 
minimum   width   of   top   plate  will   determme  the  packing   u, 
the  bottom  chord  ;  so  that  the  next  step  will  be  the  i)roiK)rti(iii 
ing  of  the  top  chord. 

Let  us  take  first  the  stress,  58.103,  and  try  nine-inch  chan- 
nels, which  will  give  26\  as  the  ratio  of  length  to  least  diameter 
Referring  to  Table  X.  f(u-  both  ends  fixed,  we  find  3  226  for  26,] 
diameters,  so  may  use  3.222,  which,  divided  into  58.103,  gives 


ORDINARY  IROX  HIGJlirA  V-nRlDGES.  ,3, 

.8,03  square  inches.     From  p.   ,5  we  find  that  the  minimum 
.si.e  of  top  plate  for  nine-inch  channels  is   A"x  iii"    00^ 
sponchn,  to  an  area  of  3.59  square  inches,  ''suhtracti^rt    s 
from  IS  03,  and  dividing  the  remainder  by  2,  gives  7  -..  sauare 
.nche.s   for  the  area  of  one  channel.   whLh'  corrc^s  01;,'  to 
wc.g  t  per  foot   of  24.07  pounds.*      Referring  to  CanJ^'s 
"locket-Compan.on."  p.  65.  we  find   that  ninlinch   chapel 
vary  in  weight  from  eighteen  to  thirty  pounds  per  foot ;  so  t  e 
n.ncnch  channels  required  will  be  procurable      This  cakula 
-;-;  .s  not  final,  for  it  is  not  improbable  that  ten-inc^cl  atn  Is" 
will  he  found  more  economical.  ^'idunus 

The  best  way  to  settle  the  point  is  to  ascertain  the  average 
weight  per  foot  of  chord  for  both  cases.  Dividing  then  TT^. 
and  61  976  by  3.2^^   subtnrMn<r  ,  ,r.  (  u  ^'  '  ^^  " 

,■  ,  •  ^\  ^  ^  ."  ^"'^^'^^ctuig  3.59  from  each  quotient,  mul- 
t.l)  y,ng  the  remainders  by  10.  and  dividing  by  6.  ^ives  18  o7 
and  36.08  as  the  weights  of  the  channel  bars  for' h  ?  cond  and 
ourth  panels ;  which  weights  are  both  procurable.  Thc^av  ra"e 
of  the  three  sections  will  therefore  be  iy.2s  square  inches  co^r 
responchng  to  a  weight  per  foot  of  57-43  pounds.  ' 

It  we  employ  ten-inch  channels,  the  ratio  of  len-th  to  least 
d-anicter  will  be  24.  tor  which  Table  X.  g.ves  3  360  as  the  !n 
t.ns,ty  of  working-stress.     Dividing  this  7nto  eacf  ^f  ^^^^ 
.-.se.s  gives  18  40.  ,7.35.  and  ,3.80  as  the  sections  required 
Ihc  muumum  s.ze  of  top  plate  (see  p.   .5)  is  A"x  r'l"  cor 
ro-sponchng  to  an  area  of  3  9.   square  inches.     Subtracting  tht 
from  ,3.80.  and  mulfplynig  the  remainder  by  ^    "ves   16.8 
I-nuls  per  foot  as  the  weight  of  the  channels  'n  U  e^     1  p  nd 
'1-  top  chore,     but  the  lightest  ten  inch  channel  proc  , "^1 
-■    Carnegie,  p.  64)  weighs  seventeen  and  a  half  pound     per 
f'-t:  therefore  the  area  of  the  section  will  have  to  be     4^4 
■Mliiare  mehes.  4-4i 

TlK'  a^•erage  of  the  three  sections  will  be  ,6.69  square  inches 

dllwt:"  "f  '^ '  "^'^'^ ''  ''■''  ^"""^'^  i-^ "-''  foot  ^ 

'l.ilucnce  between  57  43  and  55.63  is  1.8.  which,  multiplied  by 


Th: 


8.103.  iiivcs 


il 
111 


III 

^ftjp 

ffi^M 

IH 

1  i 

K:    9 

m   V' 

If 

n2 


OA'/)/x.un-  iROx  i//(;nir.\y-i!R/in;Es. 


IIIIP^'^ 


240,  the  total  length  in  feet  of  the  two  top  ehorils,  gives  433 
pounds  as  the  apparent  saving  of  iron  in  the  chords  hy  usin;; 
ten-inch  channels:  to  this  must  he  added  the  saving  in  the 
batter  braces,  which  could  be  calculated  in  the  same  way.  It 
is,  however,  unnecessary  to  make  this  calculation  ;  for  we  can 
see,  that,  all  things  considered,  it  is  better  to  adopt  the  ten-inch 

channels. 

The  sections  and  weights  of  the  top  chord  panels  are  now  to 

be  entered  on  the  diagram. 

It  is  about  time  to  look  to  the  bottom  chord  packing,  and  see 
if  there  be  sufficient  room  inside  the  posts  for  the  diagonals 
and  beam  hangiM-s;  but  we  must  f^rst  proportion  the  diagonals  as 
marked  on  the  diagram  by  means  of  the  table  on  pp.  94,  95,  of 
Carnegie's  "  Pocket-Companion,"  and  the  hangers  by  referring 
to  Table  XXII  ,  which  shows  that  I"  square  bars  will  be  required, 
square  bars  being  adopted  because  there  will  be  very  little  room 
to  spare  inside  the  posts.     Referring  to  Table  XXVIII..  we  find 
the  width  of  flange  for  a  10"  24.15*  channel  to  be  2.63  inches. 
Doubling  this,  and  subtracting  the  product  from  the  width  of 
plate,  leaves  7  24  inches  for  the  width  between  channels.     The 
thickness  of  the  inner  splice  plate  will  be  about  seven-si.xtcenths 
of  an  inch;  doubling  which,  adding  an  eighth  of  an  inch  for 
play,  and  subtracting  the  sum  from  7.24,  will  leave  6.24  as  the 
distance  between  inner  faces  of  post  channels      The  thickness 
of  each  inner  re-enforcing  plate  at  the  foot  of  a  post  cannot 
exceed  half  an  inch,  which  would  leave  5.24  inches  for  packing 
the  diagonals  and  hangers.     For  the  second  and  fourth  panel 
points  this  will  be  sufficient  ;  but  at  the  third  there  would  he 
room  enough  to  let  the  counters  in,  and  not  enough  to  permit 
of  turning  up  the  sleeve  nuts.     We  can  either  substitute  a  single 
counter,  or  widen  the  chord  plate.     The  former  will  be  prefera- 
ble, as  the  counter  stresses  do  not  affect  the  sizes  of  the  bottom 
chord  pins,  and  the  central  pin  of  the  upper  chord  should  have 
an  excess  of  strength  in  any  case. 

From  Table  IX.  we  find  that  the  size  of  the  counter  required 
will  be  i^ig"  square. 

Ne.xt  let  us  proportion  the  batter  brace.     The  ratio  of  length 
to  least  diameter  is  about  37.],  for  which  Table  X.  gives  2.639 


(>A'/)/A:IA'}'  /A'O.V  IlICIlWAY-liRIDGES. 


m 


s  are  now  to 


unter  required 


as  the  intensity  of  workings  stress,  which  divided  into  42.315 
oives  16.03  as  the  section  required.  Sul)tracting  3,91,  and  mul- 
tiplying the  remainder  by  Y-  gives  20.2  pounds  per  foot  as  the 
weight  of  each  channel  of  the  batter  brace. 

Next  let  us  proportion  the  posts.  We  see  immediately,  from 
the  small  stress  in  the  centre  post,  that  its  section  will  be  the 
smallest  ever  used,  viz.,  that  of  5"  ;#  channels  [vide  p.  8):  so 
there  is  no  need  of  calculating  the  section  required.  Let  us 
assume  six-inch  channels  for  the  next  post :  the  number  of 
diameters  will  then  be  forty-eight,  and  the  intensity  for  two 
hinged  ends  1.335.  which,  divided  into  10.05,  g'ves  7.53  square 
inches,  corresponding  to  two  12  55-pound  channels.  These  are 
not  so  economical  as  seven-inch  channels  :  so  we  will  try  the 
latter.  The  ratio  is  41  J,  and  the  corresponding  intensity  1.656, 
wiiich  divided  into  10.05  gives  607  .square  inches,  correspond- 
ing to  channels  weighing  10.12  pounds  per  foot.  The  smallest 
procurable  seven-inch  channels  weigh  10.5  pounds  per  foot, 
which  size  we  will  therefore  adopt. 

I. "t  us  assume  nine-inch  channels  for  the  next  post,  making 
tlie  ratio  32,  and  the  intensity  2.193,  which  divided  into  17.25 
gives  7.86  square  inches,  corresponding  to  channels  each  weigh- 
ing 13. 1  pounds  per  foot.  As  the  lightest  nine-inch  channels 
weigh  14,5  pounds  per  foot,  it  will  be  necessary  to  employ 
these,  unless  eight-inch  channels  be  more  economical  Let  us 
try.  The  ratio  is  now  iC\  and  the  intensity  r.937;  making  the 
area  8.91,  and  the  weight  of  one  channel  14.S5  pounds  per  foot, 
On  account  of  the  smaller  sizes  of  lattice  bars  and  stay  plates, 
tlie  eight-inch  channels  will  prove  more  economical,  in  spite  of 
their  larger  section  :  so  we  will  adopt  them. 

Xext  let  us  proportion  the  bottom  chord,  recollecting,  that,  in 
the  two  end  panels,  an  allowance  must  be  made  for  one  rivet 
hole  in  each  inner  bar,  the  rivets  being  half  an  inch  in  diameter. 
It  is  to  be  noticed  that  the  proportion  of  width  to  depth  of 
chord-bars  in  the  centre  panels  is  about  one  to  five,  because 
there  are  four  bars  in  a  panel,  and  that  the  depth  of  the  end 
I'anel  bars  approaches  the  limit  for  stiffened  bars, 

I'rom  Table  VL  we  find  the  size  of  the  hip  verticals  to  be 


KJ 


square. 


134 


OA'D/.y.lNV  /A'O.V  1 1 ICllWAV-n RIDGES. 


\f 


Next  let  us  determine  the  sizes  of  the  pins. 

If  we  tai<e  the  average  thiekness  of  one  chord  bar  at  the 
centre  of  the  span  to  be  \\",  we  make  a  little  allowance  for 
accidental  thickenini;  of  the  heads. 

Substituting  in  the  formula  given  on  p.  85,  viz., 

M=      -, 
2 

we  find  the  moment  to  be  23.56  inch  tons,  and,  referring  to 
Table  XII.,  determine  the  size  of  the  pin  to  be  3^".  The  least 
allowable  diameter  of  pin  for  a  3J"  bar  is  3.75  X  0.8  =.  3":  so 
we  will  use  3|"  pins  for  the  five  middle  panel  points  of  the 
bottom  chords.  The  chord  bars  of  the  end  panels  being  neces- 
sarily out  of  proportion,  we  have  to  use  at  the  pedestals  and 
first  panel  points  pins  2|"  in  diameter,  the  smallest  that  can 
be  used  with  bars  3|"  deep.  It  may  be  well  to  check  the 
size  of  these  pins.     The  horizontal  component  of  the  moment 

I         ''T  I 

on  the  pin  at  the  first  panel  point  is  -  X  -^^-  ^d.'i  mch  tons, 

nearly.  The  stress  in  one  hip  vertical  is  equal  to  one-half  of  the 
section  required,  as  given  in  Table  VI.,  multiplied  by  the  inten- 
sity of  working-stress  for  hip  verticals,  or  .]  X  2. 14  X  4  =  4.2S 
tons.  This  may  be  assumed  without  appreciable  error  as  the 
load  on  a  hanger.  The  sum  of  the  thicknesses  of  a  hip  vertical 
and  a  hanger  is  almost  2  inches,  making  the  lever  arm  1  inch, 
and  the  moment,  about  4.3  inch  tons.  The  total  moment  is, 
therefore,  y'iG.S)- -j- (4!^  =  8  inch  tons,  which  corresponds  to  a 
2|"  pin ;  so  that  the  diameter  previously  determined  is  ample. 

Next  let  us  find  the  size  of  the  hip  pin.  From  the  lormula 
on  p.  86,  and  Table  XXVIII.,  we  find  that  the  appro.ximato 
thickness  of  the  bearing  is  about 


M-4 
2  X  10 


+  0.3  =  1.02  ,  say  I 


The  lever  arm  for  the  diagonal  stress  will  be  1^'",  say  i",  and, 
for  the  hip-vertical  stress,  ^"  +  ^(i"  +  i  Vfi  ")  —  ^^^""t  2",  and  the 
corresponding  moments  respectively,  15.6  and  2  X  4.28  =  8.6 
inch-tons.  Laying  out  these  moments  in  their  respective  direc- 
tions, we  find  the  resultant  moment  to  be  about  22.7  inch  tons. 


ON/)/X.lA'y  /KOX   llICllUWY-liianGES.  135 

which  crresponcls  to  a  diameter  of  3]".  The  resultant  of  the 
stress  on  one  end  diagonal  and  one  hip  vcrtieal,  found  by  dia- 
gram, IS  about  19  tons.  Looking  in  Table  XXVI.,  vvc  find  that 
a  ])earuig  of  \"  is  sufficient. 

Next  let  us  find  Jie  size  of  the  next  chord  pin  from  the  hip 
iM-om  the  formula  on  p.  %G,  and  Table  XXVIII.,  we  find  that 
the  appro  imate  thickness  of  the  chord  bearing  is 

'17-25 

r^io  +  °-4S  =  1-3 1  inches, 

and  that  of  the  post  bearing  (p.  87), 

8.91 

— g-  =  1.11  inches. 

Allowing  a  little  for  play,  the  lever  arms  for  the  vertical  and 
iiun/ontal  components  of  the  stress  on  a  diagonal  are  respec- 
tively 1  and  2|":  the  components  found  by  diagram  are  about 
•S  tons  and  6.7  tons  respectively,  making  the  moments  8  inch 
tons  and  .5.1  inch  tons,  the  resultant  of  which  is  17.  i  ^nch  tons 
corresponding  to  a  diameter  of  2^.  This  is  large  enough  fo,^ 
a  three-inch  bar.  There  is  no  need  of  testing  for  bearin-  A 
snn.Iar  nivestigation  for  the  ne.xt  panel  point  shows  that  a  2]"  pin 
will  be  recpured,  which  size  will  also  be  used  for  the  central  pin 

By  referring  to  Table  XXV.,  we  can  write  upon  the  diagram 
the  sizes  of  all  the  lateral  and  vibrati.^i  rods  and  the  sections 
"I  the  upper  lateral,  portal,  and  intermediate  struts  It  will  b- 
sufficient  to  write  the  sizes  of  post  vibration  rods  and  interme- 
diate struts  on  one  post  only,  as  they  are  of  the  same  dimen- 
sions throughout  the  bridge. 

i'lom  ]).  54  we  take  the  formula 


) 


tn  find  the  stress  on  the  end  lower  lateral  strut  between  expand- 
""■•  Medestals.     Here 


in 


n  =  S 

^=  2.375  (seep.  10) 

cos  6  =  0,57 


_  7;5  X  30  X  20 


2000 


2000 


59-2 


7c'  =  i-5_^  >50J<^o  ^ 
2000 


=  2.25 

0-7S 


I 

m 


I  ^/) 


ORn/X.lA']-  Jh'OX  IIHUIWAV-nRIDGES. 


and  r(i7V/r  Appendix  I)  =  one-half  the  lenj^th  of  span  multi- 
pHed  by  the  release  of  pressure  per  lineal  foot  on  the  windward 
truss,  or 

80  X  30  X  lo  X  9 

^ — =  7.2  tons. 

15  X  2000  ' 

Substituting  these  values  gives  C„  =  9.2  tons.  Assuming  four- 
inch  channels,  the  ratio  of  length  to  least  diameter  will  be  43, 
for  which,  with  one  fixed  and  one  hinged  end,  Table  XI.  gives 
an  intensity  of  2.245  :  therefore  the  section  required  is  4. 1 
square  inches,  corresponding  to  two  6.83*  channels.  It  will 
be  more  convenient  for  riveting  to  use  5"  ;#  channels.  At  the 
fixed  end  of  the  span  a  5"  10*  I  will  answer  for  a  strut  between 

pedestals. 

We  are  now  ready  to  proceed  with  the  "Bill  of  Iron,"  in 
making  which,  close  approximations  of  lengths  are  allowable. 

Let  us  prepare  the  blank  form  recommended  in  Chapter 
XIV.,  then  turn  to  the  list  of  members  given  in  Chapter  HI., 
and  fill  out  the  form,  proportioning  as  we  go  any  details  whose 
sizes  have  not  been  previously  determined.  The  filling-out  of 
the  part  denominated  "Alain  Portions"  is  a  very  simple  matter, 
and  needs  but  little  explanation.  It  is  to  be  noticed  that  the 
lengths  of  the  chord  bars  and  main  diagonals  have  been  in- 
creased by  three  feel  to  allow  for  the  weights  of  the  heads,  and 
those  of  all  adjustable  rods  by  five  feet  to  allow  Un-  the  weight 
of  the  eyes,  upset  ends,  and  adjusting-nuts.  The  intermediate 
and  portal  struts  are  placed  seven  feet  below  the  level  oj  the 
upper  chord  i)ins,  so  as  to  allow  a  clear  headway  of  fifteen 
feet. 

The  size  of  the  floor  beam  is  taken  from  Table  XIX. 

The  grouping  of  members  having  some  similar  dimensions 
is  to  be  observed.  It  involves  considerable  economy  of  labor, 
if  one  has  to  estimate  on  many  bridges.  In  filling  out  the 
last  vertical  column,  the  tables  on  pp.  8S-93  and  104-109  of 
Carnegie's  "  Pocket-Companion  "  will  be  found  very  useful. 
Let  us  employ  latticing  for  the  top  chords,  batter  braces, 
posts,  and  portal  .struts,  and  single-riveted  lacing  for  the  latenil 
struts. 


'/>'/V.\./AT  /A'(;.\-  lHuUWAV-liRIlKIE 


\17 


kofcirin-  to  Tables  XXXII.  and  XXXIII. 

uf  stay  plates  for  the  top  chords  and  hatter  b 

iV'  X  8",  since  d  =  0.75/?/ 
that  for  the  middle  posts, 

i"  X  5^",  r/ being  equal  to  i.i^D; 


we  find  the  size 
races  to  be 


ha 


t  for  the  next  larger  ])osts, 


J"  X  6J",  d  being  equal  to  D; 


that  for  the  larirest 


posts, 


/fi"  X  6J",  ^/ being  equal  to  0.88Z), 


that  for  the  portal  struts, 


}"  X  4f ,  ^/ being  equal  to  i.i8Z>, 


tliat  for  the  upper  lateral  strut; 


^"  X  8",  since  ^/  exceeds  2D! 
that  for  the  end  lower  lateral  strut. 


;nu 


i"  X  9",  ./ 


:)cm 


g  equal  to  about  i.5Z>. 


It  at  the  hip  joint  we  make  the  thickness  of  each  inner  and 
nutcr  connectin-plate  I",  the  cross  section  of  the  plates 
thn.u-h  the  pin  hole  by  a  plane  ])erpendicular  to  the  len-^th  of 
the  batter  brace  will  be  -reater  than  either  that  of  the  Trntter 
)racc  or  that  of  the  end  panel  of  the  top  chord  :  moreover,  the 
bcarmg  will  be  slightly  in  excess  of  that  needed  to  resist 
the  stresses  in  an  end  diagonal  and  a  hip  vertical,  so  we  may 
conclude  that  these  thicknesses  will  suffice. 

Without  committing  any  grave  error,  we  may  assume  that  the 
total  stress  m  the  end  jx.nel  of  the  chord  is  equally  divided 
between  the  four  connecting-plates,  making  that  on  each  plate 
about  1 1.6  tons. 

The  thickness  of  the  web  of  a  10"  .7.5*  channel  is  03" 
^sce  lable  XXVIII.) :  therefore  the  lever  arm  for  the  stress  in 


I 


'I     H   1- 

lllll 


ll! 


.fif. 


lit!' 


I  ;vS 


ch'n/x.ih'V  /h'lKX  II  hill  WW  v-iiRiih;i:s. 


a  cnnnoctin^'-phitc  is  il(o.3 -}- o.3;5)  =0.338  im-Ii,  making  the 
niotncnt  1 1/)  X  0.33S  =  3.93  incli  tons,  whifh  divick-d  by  0.31  1, 
the  rosistin^'-ni(iiiu-nt  fur  a  '■'('  rivet,  as  ^ivcu  in  'I'ablc  XXXV'I,. 
ni\cs  thirteen  as  tlic  number  of  rivets  rec|iiire(l  to  resist  l)en(l- 
ill^^  I'"roni  the  same  table  we  fmd  by  interpolation  about  \.},() 
tons  as  the  bearin^^-resistance  for  a  |"  rivet  on  a  0.3"  plate. 
The  stress  tran.sferred  to  the  channel  is  2  X  1 1'')  =  -l-~  tons, 
which  divitled  by  1.36  <;ives  seventeen  as  the  number  ol 
rivets  recpiired  for  bearing;.  It  will  be  convenient  to  u.^e 
sixteen  rivets,  in  four  rows  of  four  in  a  row.  We  can  do  so 
Ic^ntimately,  as  the  calculation  calling  for  seventeen  is  merely 
approximate. 

It  is  evident,  without  calculation,  that  sixteen  rivets  will  be 
enough  for  the  connecting  plates  on  the  batter-brace  side  ot 
the  pin  hole,  for  the  stress  is  less  and  the  thickness  of  web 
sliglitly  greater. 

To  make  the  outer  plate  fit  between  the  flange  rivet  heads, 
we  cannot  have  it  much  more  than  seven  inches  wide,  unless 
the  said  rivet  heads  be  countersunk. 

Next  let  us  lay  out  the  hip  to  scale,  as  in  the  accompanying 
figure,  spacing  the  rivet  holes  according  to  the  rules  given  in 
Chapter  II.,  and  allowing  three  inches  of  length  extra  for  thr 
part  which  connects  with  the  batter  brace,  so  as  to  i)r()vide  for 
the  i)ortal-strut  connection.  This  api)roximation  is  accurate 
enough  for  a  bill  of  iron.  The  circles  arc  those  for  the  pin  ami 
the  limiting  distance  for  non-countersunk  rivets.  The  rivet 
spacing  is  three  inches  along  the  hori/jMital  lines. 

To  calculate  the  weight  of  an  inner 

f!' '">- ^       plate,  we  may  divide  it  into  two  jiarts 

'^i  by  the  line   ///)   in  the  figure,      llic 
:hJ  area  of    the    lower    part    is    ecpial    to 
the  length  of  CD   multiplied   by  the 
^r  perpendicular    distance    between   AH 

and  Gil,  anil  that  of  the  upper  part 
by  one-half  the  product  of  AB  and 
EF.  These  dimensions  are  recorded  approximately  in  the 
"Bill  of  Iron."  The  length  of  the  outer  connecting-plate  is, 
of  course,  measured  along  its  centre  line. 


ou/>/.v.iA'y  iRox  mGiiivAv-nRin^jEs,  ,39 

n^c-arca  of  a  section  of  the  four  conncctinj^-platos  at  the 
rst   .n  ermechate  ,anel  point  of  the   top  ehoni  'sho.id   .,.. 
tlua  ea  of  a  sect.on  of  the  two  chord  channels  of  the  third 
I'l'icl,  or  13.34  square  inches.     Let  us  use 

two   i"  X  10"  =7,5    , 
and  two  ^"  x     7"  =  6.12  j  ~  '•'•^^  square  inches. 

The  stress  carried  by  the  channels  of  the  third  panel  is  ecmal 
o^    hur  area  nudt.plied  by  the  intensity  of  wori<in,.stressI  or 

,v.,4X3.3^>9^44y4  tons;  which  may  be  divided  equally 
between  the  four  plates,  making  the  stress  on  each  plate  cihout 
....  t.>n.  Table  XXVIIi.  ,ives  the  thickness  of  .ll^  of  a  l^' 
-..-3*  channel  as  0.45  inch,  which  will  make  the  lever  arm 
-      the  stress  on   the  outer  plate   i(o.45  +  0.43)  =  0.44    inch, 

.1    the  moment    11.2X0.44  =  4.93   inch  tons,  which  divided 
a..'  «.'^'^''^  "^^^^  ^^  the    number  of  rivets    rec,uire<l    to 

IiKiinnt;  ujjon  bearmg. 

be'takJn  ar'''""  '''''  "^  '^'  ^"'"'  '^"  '''''''  ""  '^'  '^^^""^''^  "^^X 

'0-5  X  3.369  =  35-37  tons, 
or  ai)()ut  8.8  tons  per  plate. 

Thc^levx-r  arm  is  .J(o  3  +  0.43)  =  0.36  inch,  makin.  the  mo- 
•  H nt  .S.8  X  0.36  =  3. 17  .nch  tons,  which  divided  by  0,3,1  -nves 
e^ven  as  the  number  of  nvets  to  resist  bendin,.     Dividin;,7.6 
b>  i.36  gives  thirteen  as  the  number  of  rivets  to  resist  bearim^  • 
or  convenience  we  can  call  it  twelve,  as  the  stress  is  not  quite 
M.  g,eat  as  we  as.sumed  it.     It  is  to  be  observed  that  at  the  h  , 
e  sun>ose  that  all  the  chord  stre.s  is  carried  by  the  conn  ^ ' 
".^-plates.  whde  at  the  ne.xt  panel  point  we  assume  that   the 
jnnncc  >ng.plates  carry  only  the  portion   of  the   stress   trans- 
over  Plate  '   rr^'^'  ""'  r'"""'^"  '""^  transmitted  by  the 
over  plate.      The  reas(,n   for  this  is,  that  the  cover  plate  at 
tbc    .p.  ben.g  bent,  cannot  be  relied  upon  to  carrv  stress. 
At  the  next  panel  point  the  stress  on  one  plate'is 


14.49  X  3.;,6(; 


—  I  2.2  tons. 


8  i  i 


11'' 


Vl%:^ 


te 


140 


Oh'n/XANV  /A'O.y  inuini-AV-BRIDGES. 


The  sections  of  the  plates  will  have  to  be 


two  T^' 


X  I 


o   —  S.75  j  _  j^  gg  gquare  inches. 


two-rV'X    7"  =  6.13) 
The  thickness  of  the  web  is  found   to  be  0.5":  therefore  the 
lever  arm  is  |(o.5  +0.43)  =0.46  inch;  and  the  moment,  12.2 

X  0.46  =5.61  inch  tons,  which  divided 
by  0.31 1  gives  eighteen  as  the  number  of 
rivets  for  bending. 

To  find  the  lengths  of  the  connecting- 
plates  we  must  make,  as  before,  a  drawing  to  scale,  as  in  the 
accompanying  diagram.  We  thus  determine  the  length  of 
plates  for  the  first  intermediate  connection  to  be  thirty  inches. 
The  length  of  the  plates  at  the  next  panel  point  will  be  greater 
by  the  space  required  for  si.x  rivets,  or  thirty-four  inches  and 
a  half,  and  that  at  the  middle  panel  point  greater  by  the  space 
required  for  eight  rivets,  or  thirty-si.x  inches. 

Continuing  down  the  "  List  of  Members,"  we  come  to  the 
re-enforcing  plates  on  bottom  chord  struts.  Let  us  make  them 
J>J'  X  3"  in  section.  It  is  not  worth  while  to  calculate  the  num- 
ber of  rivets  required  to  connect  them  to  the  web  of  the 
I-beam  ;  because  four  five-eighths  inch  rivets  will  give  an  excess 
of  strength,  making  the  length  about  ten  inches.  Next  come 
the  shoe  connecting-plates.  Let  us  em])loy  the  connection 
illustrated  in  Plate  VI.  From  Table  XXVI.  we  find  the  thick- 
ness of  bearing  for  a  2§"  pin  and  a  stress  of  13.6  tons  to  be  I"  \ 
subtracting  from  which  0.38",  the  thickness  of  web  of  batter- 
brace  channels,  leaves  l"  for  the  thickness  of  the  re-enforcing 
plate.  Assuming  the  greatest  width  of  plate  in  a  direction 
perpendicular  to  the  length  of  the  batter  brace  to  be  sixteen 
inches,  gives  the  sectional  area  of  the  connecting-plate  equal 
to  sixteen  square  inches,  or  that  of  the  batter  brace  :  so,  pro- 
vided we  have  such  a  width,  the   half-inch   plate  will   answer 

the  purpose. 

The  .stress   carried   by    the    batter-brace   channels    is    12.12 

X  2.639  =  32  tons,  nearly,  or    i6  tons  on  one   channel.      The 

iever  arm  of   this  stress  is  .](,]  +  «)  = -Jg",   anc.    the    moment, 

T    X  16  =  7  inch  tons,  which   divided    by  0.493,  the  resisting- 


ORDIXARY  IRON  HIGHWAY-BRIDGES, 


141 


nioiiK-nt  of  a  seven-eighths  inch  rivet,  gives  fifteen  as  the  num- 
])cr  of  rivets  required  to  resist  bending.  It  is  better  to  use 
seven-eighths  inch  rivets  here,  on  aceount  of  their  large  bcnd- 
ing-resistance.  Tliere  is  no  need  of  calculatinjr  for  bearin-- 
'lo  deternunc  the  dimensions  of  the  connecting-plate,  we  will 
jH-oceed  as  follows ;  t'he  distance  between  the  channels  at  the 
shoe  being  12.5"  —  2  X  2.51"  =  7.5". 

In  the  accompanying  diagram  let  us  lay  out  a  centre  line 
AB,  and  the  two  parallel  lines  CD  and  EF  each  at  the  distance 
3 1'  from  AB.  h'rom  any  point  A  lay 
niT  the  lines  ACG  and  AEH,  makin"; 
angles  with  AB  equal  to  the  inclination 
(if  the  batter  brace  to  the  horizontal, 
join  CE.  Draw  the  lines /A' and  EM 
parallel  to  CG  and  EII,  and  ten  inches  a 
therefrom  :  draw  also  the  centre  lines 
XO  and  PQ.  To  allow  sufficient  clear- 
ance for  the  chord  heads,  the  pin  holes 
sliould  be  five  inches  and  a  half  above 
the  top  of  the  shoe  plate.  By  crowd- 
ing the  rivets  as  near  as  possible  to  the  flanges  of  the  channels, 
\ve  are  able  to  use  four  rows.  Laying  out  the  circles  for  the 
pm  holes,  and  limiting  distance  for  rivet  centres,  we  determine 
the  height  of  the  box  plate  to  be  about  14". 

If  the  vertical  sides  KD  and  iMF  be  adopted,  the  shoe  plate 
will  be  28"  long,  which  is  probably  too  much.  To  ascertain, 
let  us  find  the  number,  size,  and  arrangement  of  the  rollers. 
The  total  pressure  on  one  shoe  is 

,        ,        i860 

i  X  160  X =  37.2  tons. 

2000      ^' 

Let  us  assume  the  dimensions  of  a  roller  to  be  2"  ■^)  by  12". 
Turning  to  Table  XXXIV.,  we  find  the  permissible  pressure 
on  such  a  roller  to  be  424  tons,  which  divided  into  37.2  gives 
nine  rollers.  Spacing  them  3"  centre  to  centre,  and  allowing  a 
projection  of  i.]'at  each  end,  would  make  the  shoe  plate  29" 
long.  A  plate  12]"  X  2i)'  is  not  a  very  good  shape.  Let  us  try 
rollers  2]'V  by  15",  the  permissible  pressure  for  one  of  which  is 


I  Mill  118  ^ 

B   i-U    p 


'I  Im 


ii?  * ' 


li 


142 


OA'nLV.lA'V  INOX  HiaHWAV-BRIDGKS. 


5.63  tons  ;  making  the  necessary  number  (37.2  -^  5.63)  seven. 
Spacing  them  3|",  and  allowing  the  same  projection  as  before, 
will  make  the  shoe  plate  15]"  X  25",  a  better  shape.  Allowing 
the  shoe  plate  to  project  3"  beyond  the  front  end  of  the 
channels  will  make  the  length  of  the  connecting-plate  22", 
which  distance  is  laid  off  from  C  to  R.  The  perpendicular 
distance  of  A'  from  AG  exceeds  16":  so  a  plate  of  the  shape 
CGKRSMHEC,  before  bending,  will  fulfil  all  the  require- 
ments. To  find  its  weight  let  it  be  divided  into  a  rec- 
tangle, two  triangles,  and  two  parallelograms,  as  indicated  in 
the  "Bill  of  Iron." 

The  next  details  on  the  "  List  of  Members  "  are  the  re-enfor- 
cing plates  at  feet  of  posts.  From  Table  XXVI.,  we  find  that  a 
2)\"  pin  requires,  for  a  stress  of  8.6  tons,  a  bearing  of  less  than 
half  an  inch,  but,  in  order  to  compensate  for  a  slight  trimming 
of  the  flanges  of  the  channels,  there  must  be  a  plate  on  the 
inside,  and  another  on  the  outside,  of  each  channel ;  and  the  least 
thickness  for  one  of  these  plates  is  three-eighths  of  an  inch. 
We  will  not  trim  the  five-inch  channels,  so  will  not  have  to  use 
an  outer  re-enforcing  plate  :  this  is  because  there  would  be  no 
room  for  a  3,|"  pin  through  such  a  plate.  The  requisite  length 
for  these  plates  cannot  be  exactly  determined ;  for  it  is  impos- 
sible to  say  how  much  of  the  bearing-stress  is  taken  up  by  the 
web,  and  how  much  by  each  plate.  Let  us  assume 
that  the  inner  plate  of  the  largest  post  channel 
takes  up  half  the  stress  on  the  channel,  or  4.3 
tons.  Table  XXVIII.  gives  the  thickness  of  the 
web  as  0.35  inch.  Using  |"  rivets,  and  figuring 
S  for  bending  and  bearing,  we  find  the  number  of 
j  rivets  required  to  be  nine.  Laying  out  to  scale 
I  the  foot  of  the  post,  as  in  the  accompanying  dia- 
^  gram,  and  allowing  five  inches  and  a  half  between 
the  centre  of  the  pin  hole  and  the  foot  of  the  channel,  we  find 
that  the  required  length  of  plate  is  sixteen  inches.  In  the 
same  way,  the  lengths  of  the  re-enforcing  plates  at  the  feet 
of  the  other  posts  might  be  calculated :  but  it  is  hardly  worth 
while  ;  for,  if  we  make  them  all  of  the  same  length,  they  will 
be  sufficiently  strong  without  causing  much  waste  of  material. 


^ 


1 


ORDLXARY  IRON  HIGHWAV-nRIDGES.  143 

After  entering  these  dimensions  on  the  "Bill   of   Iron '•  we 
refer   agam   to  the   "List   of   Members."  and,   after  omi'tting 
rc-cnforc.ng  plates  at  middle  of  posts,  eome  to  the  connecting 
p  a  es  for  lateral  struts  to  top  chords.     The  thickness  of  these 
plates  should  be  |".  and  the  average  width  of  the  leo-s  .1"      The 
area  of  a  4  6* channel  is  1.8  scp.are  inches,  and  the'in'tensity  of 
wo,-k.„g-stress  for  forty-two  diameters  with  both  ends  fixed  is 
by  lable  XI..  2.74  tons ;  making  the  greatest  stress  that  could 
over  come  upon  the  channel  r.8  X  2.74  =  4.93  tons.     The  lever 
a™  of  th^stress_,s,i(|  +  |)  =  ^^  inch,  making  the  moment 
]6  X  4-9o  -  2.16  mch  tons,  which  divided  by  0.380  the  resist 
,ng-moment  for  a  r  rivet,  as  given  in  Table  XXXVII    gives 
MX  as  the  number  of  rivets   required   for  attachment  '[o  the 
atcral  strut  channel.     Although  the  leverage  is  a  little  greater 
tor  the  attachment  to  the  chord-channel  flanges,  still  six  rivets 
uil;  suffice,  on  account  of  the  liberal  estimate  for  stress,  and 
us.ng  r,vet  tables  which  have  a  surplus  of  strength  for  lateral 
system  connections.     The  length  of  each  leg  of  the  T  will  be 
about  eighteen  mches,  for  various  circumstances  will  necessitate 
wide  rivet  spacing  in  this  detail. 

The  stress  and  leverage  being  the  same  in  the  two  attach- 
ments. It  IS  evident  that  six  rivets  will  be  required  at  each  ^d 
0  the  upper  channel  of  the  lateral  strut  for  connection  to  chord 
Ihere  will  be  just  room  for  this  number;  putting  two  through 
he  channe  flanges,  and  four  through  the  plate  between  t 
channels.  Were  these  not  strong  enough, 
wc  could  use  seven-eighths  inch  rivets. 

The  ne.\t  item  upon  the  "List"  is  con- 
necting-plates for  portal    struts    to    batter 
l>'aces.      These     should     have    a    greater 
strength   than  ordinary  calculations  would 
"Kl'cate,  in  order  to  provide   against   the 
niekmg  effect  of  the  wind.     If  we  use  a  jaw  plate,  as  in  the 
s    of  the  accompanying  diagrams,  and   two  bent   plates,  as 
lo  second   to  attach  to  the  flanges  of  the  strut  channels 
'       "   ^;f  ''"    "^^"-  '^'■^^^'  '''  P--^>-  ^^ainst  all  con- 
-'/'■    CD,   and   /./..     It    may  be  well    to   test    the    num- 


144 


O/^P/X.IKV   /A'OX  UlCHWAV-BRinCES. 


J)    AW 


i|il 


bci-  of  rivets  for  the  jaw  i^late,  because  it  has  to  act  as  a 
re-enforcinj;  plate  also.  I'irst  we  must  determine  the  size  of 
the  pin  which  attaches  the  vibration  rods.  The  diameter  ot 
each  rod  beinp;  i|",  the  greatest  working-stress  thereon  is  7.5 
X  0.994  =  7.5  tons,  nearly.  The  lever  arm  is  A(J  -f  |  -f  ^)  =  J". 
making  the  moment  |x  7-5  =6.56  inch  tons.  Consulting 
Table  XII.,  we  find  i '{'  ^^  the  diameter  required.  Table  XXVII. 
shows  that  there  is  more  than  sufficient  bearing.  Assuming  five 
tons. upon  the  rc-enforcing  plate,  we  find  the  number  of  eleven- 
sixteenths-inch  rivets  required  to  resist  bending  to  be 


5  x.^^}±J 
0.299 


=  6, 


so  that  the  dimensions  in  the  drawing  are  sufificient. 

Let  us  assume  the  dimensions  for  portal  connecting-plates  to 
brackets  and  name  plates  as  |"  X  S"  X  18". 

The  section  of  a  connecting-plate  for  an  intermediate  strut 
should  be  |"  X  3"  ;  and  we  will  use  three  rivets  for  the  connec- 
tion to  the  pos.c,  and  four  for  that  to  the  strut :  it  would  be 
useless  to  figure  upon  these  numbers,  as  the  stress  is  so  small. 
Owing  to  the  peculiarity  of  the  vibration-rod  connection,  each 
plate  will  have  to  be  about  two  feet  long,  as   can  be  seen  on 

Plate  VI. 

Omitting  side-brace  connection,  the  next  item  is  the  end 
lower  lateral  strut  connection  to  pedestal,  which  is  by  means 
of  a  jaw  plate  |"  X  5"-  The  stress  on  the  strut  was  found  to  be 
9.75  tons,  making  4.88  tons  on  each  channel.  The  number  of 
three-fourths  inch  rivets  required  will  therefore  be 

0.389 

There  is  no  need  of  figuring  for  bearing.     This  would  make 
the  total  length  of  jaw  jilate  about  three  feet,  as  noted  on  the 

"Bill." 

For  the  strut  at  the  fixed  end,  a  plate  .]"  X  5"  X  2'  will  answer 

the  purpose. 

The  next  item  is  the  hip  cover  plate,  which  we  will  make  of 
the  same  s  action  as  the  chord  plate,  and  eighteen  inches  long. 


ORDINARY  IROX  IfrGHlVA  V-BRIDGES. 


1.' 


2'  will  answer 


1-or  the  intermediate  joints  we  must  calculate  the  lenoths 
of  the  cm'er  plate  thus  :  the  stress  on  the  top  plate  is  3  91 
X  3.369-  13  tons  nearly;  making  the  moment  on  the  rivets 
13  X  I'^g  =4-o6  mch  tons,  which  divided  hy 
0.311  gives  fourteen  as  the  number  of  three- 
fourths  inch  rivets  required  to  resist  bend- 
ing. For  bearing,  the  number  required  will 
be  less.  The  arrangement  of  the  rivets  de- 
termining the  size  of  the  plate  is  shown  to 

scale  in  the  accompanying  drawing.     Next 

come   the    filling- plates.      Let    us    average 

those  for  the  top  chord  at  J."  thick.     For 

the  thickness  of   the   filling-plates  over  end   floor   beams    we 

"u.st  subtract  from   the  distance  between  centre  of  pin  'hole 

and  foot  of  post  the  half-depth  of  the  chord  heads  in  the  end 

l)aneLs,  thus, 


1^— 

1 

_- 1 — 

17'--* 

X     X 

xj          . 

X    X 

X     X 

X 

^ 

X     X 

X     X 

X 

X    X 

X      X 

y 

X     X 

X     X 

y 

k 

X    X 

^ 

si 

z 

5r-^(3l  X  i!  -h20)"=  If. 

The  width  will  be  equal  to  the  diameter  of  the  pin,  and  the 
length  equal  to  that  of  the  pin  between  shoulders 

Next  come  the  extension  plates.     Let  us  make  them  in  two 

th.cknes.ses,   the    shorter    piece    extending  down   to  the  stay- 

plates.     1-  or  the  largest  post,  the  total  thickness  will  have  to  be 

'  ;^'  .  or   1 1"  ;  making  that  of  each  plate  -^-9,",     Neglecting  the 

effect  of  the  stress  on  the  outer  plate,  the  moment       ,..    ,       , 

<"!  the  rivets  will   be  8.6  X  .' (O.  :!5  +  o.  s6)  =  3  gr     fl 

inch  ton.s,  which  divided  by  0.31 1  makes  the  num-    ^' 

her  of  three-c|uarter  inch  rivets   to   be  employed     f 

ei|iKil  to  thirteen.     For  reasons  advanced  in  Chap-    \ 

tcr  XII.,  we  must  count  in  only  one  half  of  those    ^ 

nvets  wh.cli  pass  through   the  double  portion  of 

the  plate  and   the  web.      Laying   off  the  end  of 

the  post   to  scale,  as   in   the  accompanying   dia- 

.i^ram,  we  determine  the  lengths  of  the  plates  to  be 

twelve  and  twenty-four  inches  lespectively      The 

nv.ts   above    the    line   AB  are   to   be  countersunk:   their   use 

's  sm.ply  to   make    the    two   plates   act    as    one.      We    mLdit 


i  i 


lil 


;■ 


IIim' 


iiii»i 


146 


ORD/.yAh')-   //cox  ///(/////'./  )'-/.' AVM/Y-'.S-. 


calculate  the  required  lengths  for  the  extension  plates  of 
the  other  posts,  but  it  woukl  be  unnecessary  labor ;  for  if,  in 
the  posts  with  the  seven-inch  channels,  we  use  two  rows  of 
three-quarter  inch  rivets,  instead  of  three,  and  in  the  posts 
with  the  five-inch  channels  two  rows  of  five-eighths  inch 
rivets,  making  the  plates  of  the  same  length,  we  will  provide 
suflficient  strength  with  very  little  waste  of  material. 

The  next  on  the  list  are  the  shoe  plates,  the  area  for  which 
we  have  determined  to  be  I5J"X25":  their  thickness  (see 
p.  16)  should  be  I". 

To  determine  the  size  of  the  roller  plate,  we  will  adopt  3" 
X  3"  5-9*  angles  to  enclose  the  rollers,  and  allow  for  a  motion 
of  two  inches,  which  would  make  the  area  2i|"X33":  the 
thickness  should  U:  I".  The  area  of  the  plate  in  square  inches 
multiplied  by  two  hundred  pounds  makes  about  seventy-one 
tons,  which  is  nearly  double  the  greatest  pressure  on  the  shoe  ; 
showing  that  the  dimeiv-.ons  decided  upon  are  large  enough. 
The  area  of  the  shoe  plate  multiplied  by  two  hundred  pounds 
per  square  inch  is  equal  to  38.75  tons;  and,  as  the  greatest 
pressure  on  the  shoe  has  been  calculated  to  be  37.2  tons,  it 
is  evident  that  we  may  use  the  shoe  plate  as  a  bed  plate  by 
properly  anchoring  it  to  the  masonry. 

Next  come  the  beam-hanger  plates.  It  will  not  be  neces- 
sary to  calculate  their  thickness,  as  the  method  was  fully 
illustrated  by  an  example  in   Chapter  XIII.;  and   experience 


would  suggest  a  thickness  of 


I'^rom  Carnegie's   "  Pocket- 


Companion,"  p.  126,  we  find  that  ^"square  bars  upset  to  i^"; 
and  from  p.  131  of  the  same  book  we  see  that  the  longest  diam 
cter  for  the  corresponding  nut  is  2.89",  say  3";  so  that,  allowing 
1"  for  clearance,  the  distance  between  centres  of  beam  hanger 
holes  will  be  /',  and  the  width  of  plate  for  full  bearing  7".  We 
can  average  the  lengths  of  the  plates  at  8". 

The  weight  of  a  name  plate  need  not  exceed  forty  pounds. 

Next  come  the  latticing  and  lacing  bars.  Referring  to 
Tables  XXX.  and  XXXI.,  we  find  for  the  top  chords  and 
batter  braces, 

where  ^/=  o  75  D,  tlie  bars  sliould  be  iV'  X  ^l"  '> 


ORDIXARY  IKON  niUHU:iV-i;RHKiES.  14; 

U)X  the  middle  posts, 

where  d=  \.^D,  they  should  be  f  X  i|"j 
for  the  next  larger  post, 

where  ./=Z>,  i"x  i|"; 
for  the  largest  posts, 

where  ^/=  o.88Z»,  1"  X  ij"j 
for  the  portal  struts, 

where,/=i.,8Z),  i"x  i^i 

for  the  upper  lateral  struts, 

where./>2Z»,  1"  X  2j-"; 
aiul  for  the  end  lower  lateral  struts, 

wherert'=  1.5Z;,  1"  X  2^". 

The  distance  between  centre  lines  of  rivets  in  the  chord  and 
batter-brace  channel  flan-es  is  about  ten  inches;  the  space 
per  panel  ni  chord  over  which  the  latticing  extends  is  about 
eighteen  feet  ;  the  corresponding  distance  in  the  batter  brace 
IS  twenty-seven  feet :  so,  if  we  space  the  rivet  holes  for  the 
latticnig  as  nearly  as  possible  ten  inches  apart,  there  will  be 
twice  twenty-two  lattice  bars  recp.ired  for  each  chord  panel 
-i  one  truss,  and  twice  thirty-two  bars  for  each  batter  brace, 
makin-  seven  hiuidred  and  eighty-four  bars  in  all.  Their 
^^^v^\^,  from  Table  XXIX.,  is  found  to  be  1. 18' +  o -'i  ;' = 
i.;i95',  say  1.4'. 

We  can  average  the  lengths  of  the  lattice  bars  for  the  posts 
thus  :  assuming  a  stretch  of  nine  inches,  a  spread  of  eight 
nuhcs  and  a  half,  and  .J"  as  the  width  of  a  bar,  gives  the  total 
length  ..034  +  0.18=1.214.  say  M' .  The  average  length  of 
space  on  the  posts  occupied  by  the  latticing  is  about  twenty 
cct  s,x  mches  ;  making  the  number  of  bars  per  post  four  times 
twenty-seven. 

The  spread,  or  distance  between   centre   lines  of  rivets   in 
channel  Hanges  of  portal  struts,  is  about  six  inches  and  a  half, 


1     (   1 
fc  r 

4 


!! 


\': 


■llUlii!' 


148 


ORIUXARV  IROX  HIGHWAY-BRIDGES. 


and  the  latticing;  extends  over  about  ten  feet  on  the  averai^e, 
after  deducting  for  various  plates  ;  which  would  make  the  num- 
ber of  lattice  bars  per  strut  about  four  times  nineteen.  The 
length  will  be  about  0.768'  +  0.145'  =  0.92'  nearly. 

The  spread  for  the  lateral  strut  rivet  centres  is  eleven  inches 
and  a  half;  and,  as  lacing-bars  are  used,  the  stretch  must  be 
about  si.\  inches  and  three-quarters  in  order  that  the  angle 
between  the  bars  may  be  sixty  degrees.  This  distance  is 
most  readily  determined  by  diagram.  The  length  of  a  bar 
is,  then,  1. 1 13' +  o.  197' =  1.31'-  The  extent  of  the  lacing  is 
about  eleven  feet,  making  the  number  of  bars  per  strut  twice 
nineteen. 

For  the  lacing-bars  of  the  lower  lateral   strut,   the  spread  of 
the  rivets  is  about  nine  inches  and  a  half,  and  the  corres])ond 
ing  stretch  about  six  inches.     The  length  of  the  lacing  is  about 
eleven  feet,  and  the  number  of  lacing-bars  twice  twenty-two. 
The  length  of  each  bar  is  0.936  '-f  o.  197'  =  1. 1 33'.  s^V  1 1'. 

Next  mi  the  "List"  comes  the  chord  trussing,  of  which  we 
will  assume  the  section  to  be  |"  X  3".  I^Y  ^  I'O".'^!"'  approxima- 
tion, we  can  find  the  average  length  for  one  panel  of  one  truss 
to  be  about  thirty-three  feet.  The  lengths  of  the  pins  are  cal- 
culated so  as  to  include  the  weights  of  the  nuts  by  adding, 
in  most  cases,  an  inch  and  a  half  for  each  nut.  The  diameter 
of  the  intermediate  vibration-rod  pins  is  assumed  to  be  i^". 
The  lengths  of  the  bolts  include  an  allowance  for  heads  and 

nuts. 

To  find  if  there  be  any  anchorage  required  at  the  rollci- 
end  of  the  bridge,  we  must  compare  the  overturning  and  re- 
sisting moments,  or,  what  is  the  same  thing,  the  release  of 
pressure  on  the  shoe  and  the  weight  thereon  when  the  bridge 
is  empty  and  there  is  no  wind.  In  finding  the  stress  on 
the  end  lateral  strut,  we  determined  the  release  of  pressure  to 
be  7.2  tons,  and  one-fourth  the  weight  of  the  empty  bridge 
to  be  14.8  tons.  The  latter  being  more  than  twice  as  great  as 
the  former,  no  extra  anchorage  will  be  required  at  the  expan- 
sion pedestals. 

As  there  is  vertical  sway  bracing,  the  brackets  may  be  light, 
Let   us  make  them  of  2.]"  X  2.]"  4.9*  angle-iron,  and  let   them 


of  which  \vc 


OA'J)/XAA'  J '  I/W.V  HIGHU  V/  J  -BRIDGES.  149 

extend    vertically   and    horizontally    four   feet.      Allowin-   six 
inches  at  each  end  for  attachment  would  make  the  total  length 
of  a  bracket  about  6.7  feet. 
An  allowance  of  ioo#  for  ornamental  work  will  be  sufficient 
The  equivalent  len-th  of  a  beam  hanger  can  be  thus  approxi- 
mately calculated  :  twice  the  distance  from  the  centre  of  the 
pm  to  the  top  of  floor  beam  equals  11";  twice  the  diameter  of 
|.in  equals  about  6";  twice  the  depth  of  floor  beam  equals  54"- 
twice  the    length    of    hanger  below  the  floor  beam  equals  6"' 
allowance  for  two  upset  ends  and  nuts  equals  y^'-,   total  lcn..th 
e(|uals  1 10"  =  say  9'.  '^ 

Let  us  average  the  diameters  of  the  fillers  at  31",  and  their 
weight  at  io#  per  foot.     The  average  length  of  filler  is  not  far 
lioni  3  .     Special  fillers  will  be  required  at  the  free  end  of  the 
span,  so  as  to  keep  the  lateral  strut  clear  of  the  batter-brace 
channels,  also  similar  fillers  at  each   end   of  the  span   to  lie 
between  the  outer  chord  bars  and  the  channels.    Let  us  assume 
that  the  channel  flanges  are  notched  out  to  a  depth  of  one  inch  • 
then  the  thickness  of  the  last-mentioned  fillers  will  be  i  J"  and 
that  of  the  others  say  |".     Let  the  external  diameter  be '7" 
and  the  internal  diameter  2|":  the  weight  per  lineal  foot  will 
then  be  (see  Carnegie,  pp.  105-107)  128.3  -  148  =  113  5 

Turn  buckles  and  sleeve  nuts  have  already  been   included, 
and  there  are  no  connecting  chord  heads. 

Next  come  the  jaws  for  lower  lateral  struts.  From  the  cen- 
tre of  the  lower  chord  pin  to  the  top 
of  the  floor  beam  being  5.]",  the  depth 
<if  the  wooden  strut  will  have  to  be 
9";  but  the  jaws  need  not  be  more 
than  7"  deep,  as  shown  on  the  accom 

panying  diagram.  The  width  of  the  strut  need  not  exceed  7" 
>'"■■  that  of  the  jaw  plate  6".  The  thickness  of  the  latter 
sh.uild  be  \  .  The  greatest  stress  upon  any  lateral  strut,  found 
by  resolving  the  stress  upon  the  r,V'  lateral  rod,  is  about  7  tons, 
which  stress  has  to  be  resisted  by  the  rivets  connecting  the 
inner  and  outer  jaw  plates.  The  number  of  rivets  required  is 
7  X  .i  __ 
0.3X9"-'^'  ''''^'^"'1  ^^'''1  make  the  total   length  of  the  two  jaw 


-j^ 


lyv 


r^ 


i^ 


ISO 


ORDINARY  IROX  HIGllWAV-nRinC.ES. 


I';? 


plates  about  5'.  A  piece  of  6"  S.5*  chaniK/  will  be  stron;^' 
enough  for  the  bent  eye  bearing.  It  is  not  worth  while  to  cal- 
culate the  number  of  rivet«  for  the  combined  upper  lateral  strut 
jaw  and  vibration  rod  liearins;  plate :  so  we  will  average  the 
dimensions  as  in  the  "  V>\\\  ot  Iron." 

Next  on  the  "  List  "  comes  the  angle  iron  around  the  edges 
of  the  roller  plates,  which  we  will  assume  to  be  3"  X  3".  weigh- 
ing 5.9^*  per  foot.  The  length  on  one  side  is  if,  and  at  the 
end  say  4|"  on  each  side  of  the  anchor  bolt  b'^'l'.  ;  making  seven 
feet  in  all  for  each  plate. 

Next  come  the  pieces  of  channels,  which  we  will  assume  to 
be  of  the  sizes  marked  on  the  "  Bill,"  and  ne.xt  the  rivet  heads, 
for  which  wc  will  make  a  separate  bill,  then  enter  the  total 
weight  with  the  other  items.  Considerable  approximation  is 
used  in  ascertaining  the  numbers  ;  and  the  fioorbeam  rivets  are 
omitted,  for  their  weights  are  included  in  the  weight  of  the 
beams.  The  total  length  of  top  plate  for  chords  and  batter 
braces  is  about  370' :  let  us  average  the  rivet  spacing  therein 
at  iV\  making  the  total  number  2  X  37°  X  12  X  ?  =  2537. 

We  may  say  that  there  is  one  rivet  for  each  latticing  or 
lacing  bar  for  attachment  to  channels,  and  one  to  every  two 
lattice  bars  for  attaching  latticing  to  latticing.  Half-inch  rivets 
will  be  used  for  the  latter  purpose,  so  as  not  to  weaken  the  bars 
unnecessarily.  Let  us  assume  that  half  the  stay  plates  are 
attached  by  three-fourths  inch,  and  half  by  five-eighths  inch, 
rivets,  and  that  there  are  six  or  eight  rivets  per  plate.  Let 
us  average  the  number  at  each  joint  of  the  chord  at  sixty-four, 
and  at  each  pedestal,  not  including  those  through  the  shoe 
plate,  at  thirty-two ;  and  let  us  assume  eighteen  rivets  at  the 
foot  of  each  post,  six  per  bracket,  and  fourteen  per  jaw.  The 
following  will  then  be  the  approximate 


ORDIA'AIiV  IRON  H/GHH'A  V-BRIDGES, 


'51 


BILL    OK    RI\  l/r    HEADS. 


CONNECTIONS. 


2,198  (</  o.oS#=     176* 

2,080  @  O.I 6"  =     333" 

5.715  @o.25"=  1,429" 

216  @  0.40"=       86" 


Diameters. 


riatt.  to  chords  and  batter  braces 
Latticing  and  lacing  to  channels  .  , 
Latticing  and  lacing  to  tiiannels  .  , 
Latticing  and  lacing  to  channels  .  . 
Latticing  and  lacing  to  channels  .  . 
Latticing  and  lacing  to  channels  .  . 
Latticing  and  lacing  to  channels  .  . 
Latticing  to  latticing 

Stay  plates  to  channels 

Connecting-plates  to  channels  .     .     . 

Ke-enforcing  plates  to  channels   .     . 

Oinnecting-plates  to  channels      .     . 

Cimnecting-plates  to  channels  .     .     , 

Connecting-plates  to  channels  and  I 

Cover  plates  to  chord  plates     .    .     . 

Kxtension  plates  to  posts     .... 

Connecting-plates  to  shoe  plates  .     . 

Trussing  to  bars 

Liackets 

jaws 

Angle  iron  to  roller  plates   .     .     .     . 


304 
190 

44 
1,084 


432 
648 


96 


480 


440 

180 
96 
60 


84 
140 


2,198 


2,080 


r 


2,537 
784 


330 
S96 

244 

80 
368 
280 


196 


5715 


128 


32 


56 


:i6 


Total  weight  of  heads 


:.o24#,  say  2,ooo#  after  deducting  for  coun- 
tersunk heads. 


Ihc  number  of  spikes  requifed  will  be  ten  per  plank  of  fioor 
(each  piank  being  9"  wide),  six  per  post  of  Imnd  railing,  ten  per 
l)anel  for  felly  plank  to  flooring,  two  per  joist,  and  two  per  jaw  • 
•"  ;i!l,  2,rn2.     The  spikes  shoidd   be   /;,"  square   by  7"  Ion-' 


152 


O/^niXARV  /A'OA'  llli.llWAV-liRinCES. 


Consulting  Carnegie's  "Pocket-Companion,"  p.  \2<.),  we  find 
tliat  there  are  662  spikes  to  a  keg  of  150*;  so  that  we  requiri.' 
four  kegs,  or  to  *. 

With  the  exception  of  the  bolt.s  attaching  the  lateral  struts  to 
the  floor  beams  and  jaws,  each  wood  bolt  must  have  two  wash- 
ers ;  making  in  all  385,  say  400.  Each  washer  weighs  about  a 
pound. 

The  weights  of  most  of  the  nuts  have  already  been  included  : 
let  us  add  fifty  pounds  for  lock   \nd  pilot  nuts. 

The  total  amount  of  lumber  may  be  estimated  in  three  ways : 
first,  as  in  the  "Bill  of  Lumber;"  .second,  by  consulting  Table 
XV.,  which  gives  2,085  as  the  amount  per  panel,  multiplying 
this  by  8,  and  adding  515,  the  numbi.'r  of  fet't  in  the  lateral 
struts  ;  and,  third,  by  consulting  Table  I.,  which  gives  269  as 
the  weight  of  lumber  per  lineal  foot,  and  multiplying  this  by 
160  X/o-  The  first  two  methods  are  accurate;  the  last, 
approximate. 

BILL    OK    IKON. 


Top  chord  channels  .  .  . 
To[)  chord  ciiaiincls  .  ,  . 
Top  chord  channels  ... 
IJattcr-bracc  channels  .     .     . 

Po>t  channcl^s 

Post  channels 

Tost  channels 

Upper  lateral  strut  channels 
I'.nd  lower  lateral  strut  channel; 
I'ortal  strut  channels  .     .     . 

Chord  plate 

ISatter-brace  plate  .... 
Intermediate  struts,  .  .  . 
I.nd  lower  lateral  strut  .  . 
Ilottom  chord  struts     .     .     . 

Main  diagonals 

Main  diagonals 

Main  diagonals 

Counters 

Counters 

Hip  verticals  ...... 


S 
8 
S 
8 

4 

8 

8 

10 


10 ' 
10" 
10" 
10" 

5" 

I 

8" 

4" 

5" 
4" 
A" 

4' 
5" 
4" 

i" 

3« 

I 

-II 


24-15* 

17-5* 

20. 2# 

7# 
io.s# 

I4.85# 
6# 

7# 

i2.r' 

I2i" 

8#I 
io#I 
io#I 

23" 

3" 

3^' 
O 

D 

D 


34'25 


10,221 
S.I"' 

So.V^ 
900 

4,Sjo 
57(i 

l.)0 

820 
6,307 

759 


OUD/X.IKV  /A'OX  ///GI/H'A  Y-niUDGES. 


^11 


!<),  we   find 
vvc  rciiviiiL' 

al  struts  to 

two  vvash- 

^hs  about  a 

II  inchulcd  : 

three  ways : 

Itint;  Table 
niulti])lyiii,L; 
the  hiteral 
ives  2^)9  as 
ing  this  by 
;    the    last, 


io,2::i 

5.'/' 

56,V^ 

f 

900 

t 

ii/i 

J 

f)86 

•5' 
•5' 

4,Sjo 

4' 

576 
140 

■5' 

S20 

25' 

6,307 

•25' 

75V 

/ 

Si;, 

I  |i|)ci  lak'ial  rolls  ,  .  . 
U|)|)fr  lateral  rods  ,  .  . 
l'|i|)t.r  I.Utral  rods  .  .  , 
l.invcr  lateral  rods  .  .  , 
I  Kttir  lateral  rods  .  .  . 
rinvtr  lateral  rods  .  ,  , 
I.owir  lateral  rods  ,     .    . 

\  il>r;iiii)ii  rods  at  portals 

\  ilu.iiion  rods  at  jjosts    . 

1  hold  bars 

I  liMid  hars 

'  lii'id  bars 

I  liord  bars     .     .     ,     ,     , 

lliior  beams 


Tiiial  weight  of  main  portions 


Si.iy  plates  (HI  chords  and  bat- 

li  T  braces 

Slay  plates  on  posts  .  ,  .  . 
Stay  plates  on  i)osts  .  .  .  , 
Stay  plates  on  posts  .  .  .  . 
Slay  ])lates  on  u])per  lat.  struts  . 
Slay  plates  on  lower  lat.  struts  . 
Slav  plates  on  portal  struts  .  . 
l'iinnectiiig-i)lates  hip  inside  . 
I  ■'  iiinecting-plates  hip  inside  . 
I'MiiRctiny-plates  hip  outside  . 

•  uniiccliiin-plates  int.  insidu  . 
CiiiuH-clinj^-plates  int.  inside  . 
CimiRcling-plates  int.  inside  . 
CniiiicclinfT-plates  int.  outside  . 
CdniR'ctiiin-plales  int.  outside  . 
('omR'ciiiii;-plates  int.  outside  . 
<  'tiiuiccting-plates,  b.  ch.  struts . 

•  '"imecting-plates  at  shoes  .     . 

Kcenforcing  plates,  ft.  of  posts 
inside 

Ki  enforcing  plates,  ft.  of  posts 
inside 

Ke-eiil'orcing  plates,  ft.  of  posts 
inside 

Ke-enfnrcing  plates,  ft.  of  posts 

"iilsidc 

Ke-cniurcing  plates,  ft.  of  posts 

mitsiile    .    . 


4 

x\" 

4 

li" 

4 

\l" 

4 

Mr 

4 

i.'ff" 

4 

li" 

4 

I" 

S 

li" 

10 

\" 

s 

■\" 

8 

\i" 

16 

\" 

r- 

\" 

y- 
s 
16 
16 
20 
4 

1 6 
8 
S 
S 
8 
S 

4 
8 
8 

4 
16 

4 

S 
8 


27" 


A" 

\" 

i" 

/'„" 

i" 

\" 

1" 

-1 

H 
'■)" 

i" 

3" 


1  ti 

iJ." 
11! 


w 
0 
O 

o 
o 
0 
© 
0 
© 

33" 

si" 

3i" 
Jl" 
54i*  h.  b. 


i" 
V 


r' 


S" 

si" 

6J" 

6J" 

8" 

9" 

■aV 

9" 

4" 
-." 

/ 

10" 
10" 
10" 

7" 

7" 

7" 

3" 

7J" 

0" 
10" 

8" 
7" 

S" 
6" 


S" 


29.5' 
21' 

19' 

-^3' 
16' 


I2i" 

loi" 

II" 
II" 

•3i" 
It" 

8" 

3'" 
36" 

35" 

30" 

34  J" 

36" 

30" 

34i" 
30" 
10" 
22" 

7" 
i8i" 

16" 

16" 

16" 

16" 

16" 


3.4SS 


557 
3S0 

10,459 

6,104 

5;.')r3 

27S 

32 

76 

99 
150 

28 

353 

204 

250 
335 

'75 
204 

235 

123 

42 

367 


380 


'54 


ONP/XARV  IROX  J  in; /III' A  V~/lN/nGKS. 


ConnL'ctinn-platcs,  hUcial  slnit 

to  clunds 

<.'onin.'Ltiiig-|)l;itcs,  portal   strut 

to  batter  braces 

(,'oniicttiiii;-plates,  portal  strut 

to  i)alti'r  braces 

fonncctiii.n-platcs,  portal   strut 

to  bracUcts  

(,'onii(.Htin,L;-|)latcs,  portal  strut 

to  name  plate 

ConiRLliii.u-plates,  int.  strut  to 

posts 

C'oiinectiiiij;-plates,    ciul     lower 

lateral  strut      

Coiinecling-plates,    euil     lower 

lateral  strut      

Cover  plates  at  lii]is  .... 
Cover  plates  at  int.  joints  .  . 
l'"illin,i;-iilates  at  hips  .... 
FiUiug-lilales  at  int.  joints  .  . 
Filling-i)lates  over  lieanis     .     . 

I"..\tension  plates 

l'..\tension  plates 

K.xtension  plates 

I'^xtension  plates 

Extension  jilates 

I'',xlensinn  ])lates 

Shoe  jilales 

kulkr  jilates 

He.ini-lianger  plates      .     .     .     . 

Name  plates 

Lattice  bars  on  chord  and  bat- 
ter braces     

I, .mice  bars  on  posts  .  .  .  . 
Lattice  bars  on  posts  .  .  .  . 
Lattice  bars  on  posts  .  .  .  . 
Lattice  bars  on  portal  struts  . 
Laciug-bars    on    upper    lateral 

struts 

Lacing-bars    on    lower    lateral 

strut 

Chord  trussing 

Tins,  top  chord 

I 'ins,  top  chord 

I'ins,  top  chord 

i'ins,  bottom  chortl 

Tins,  bottom  chord 


8 

i6 

4 


4 

10 

8 

1 6 

4 

cS 

8 
8 
8 
4 
4 
4 

'J 

M 


7S4 
432 
4.3- 
216 

304 
lyo 

44 
S 

4 
4 
6 
10 
8 


3" 


Ml 

4 


\" 


rn 

A" 

Vr," 

T-r," 

'  4 
'.'  // 

ll! 
•I  // 

ti; 


1" 


@ 


1  li 


34 


3i 


2j" 

4" 
8" 
8" 
8" 


5" 

1 2 .'," 

10" 

10" 

-,:■" 

8" 

8" 

7" 

7" 

5" 

5" 

I  si" 

2ii" 

7" 

40# 


If' 

,6" 


3" 

0 

o 
0 
0 
0 


3' 

3' 

8.i" 
18" 
18" 


18" 
17" 
iCj" 
12" 
12" 
12" 
24" 
12" 

34" 
J  2" 

24" 

-5" 

3f 
8" 

each 

1.4' 
li' 
■r 
'i' 

0.92' 


il' 

3.3' 
16" 
1 8" 
18" 
22" 
I     20" 


'S» 


f)0 

150 
f\5 

3.1 

7« 

1S5 

?,i 
61 

360 

245 

s.s 

377 

345 
191 

So 

:.57- 
844 
7SS 

3f>S 

■tP 
S,S 

147 

120 

507 
241 


ORD/X.IRV  IRON  HIGI/IVA  Y-nRIiniF.S. 


155 


3' 

'5» 

3' 

120 

8i" 

"3 

18" 

[          60 

18" 

2> 

'50 

1.4' 


>r 


f'3 


7^ 


61 


245 

NS 

377 

34  ■- 
191 

So 

-.57- 

844 

78S 

3f'5 

HI 

SS 
6(0 
147 

I3'3 

120 

507 
241 


Tins,  ])ortal  vibration  .... 
Tins,  |)o:it  vibration      .... 

Molts,  name  |)lates 

liiilts,  vibration  rods    .... 

Holts,  anchor 

Hulls,  portal  struts  to  i)atter-br. 

Hulls,  hand-rail 

Holts,  lower  lat.  strut  to  beams 
Holts,  lower  lat.  strut  to  jaws  . 
iiolts,  folly  plank  to  floor     .     . 
Holts,   felly  plank  to  hand-rail 

posts 

Hrackets 

'  'rnaniental  work 

8 
10 

4 
10 

8 

8 

68 

49 

28 
66 

34 
14 

il" 

J?" 
1       @ 

@ 
II" 

@ 

i" 
I'll 

l" 

ill 

4 

ill 

2i"X2j" 

© 

0 

\* 

5# 
0 

8# 

© 

© 

© 

© 

© 
4.9#L 

12" 

8" 

each 

each 

3' 
each 
12" 
14" 
12" 

15" 

18" 
6.7' 

74 
61 

4 

50 
98 
64 

100 
5S 
41 

121 

75 
460 
100 

^'43 

232 

12 

6 

100 

97 

700 

•75 

-^3 

60 

2,000 

(JOO 

400 

Heain  hangers 

l'7vpansioii  rollers 

Holler  flames,  sides     .... 
Roller  frames,  rods      .... 
Hilkrs 

2S 

>4 

4 

6 

40 

8 

•4 
10 

2 

14 

111 

2\" 
1 '/ 

4 
I  // 

@ 

7"0 

7"0 
\ii 

i 
ill 

6" 

D 
0 
2" 

0 
io#  JK-r  ft. 
1 13.5*  per  ft. 
113.5*  per  ft. 
6" 
14" 
S.'# 
.S.5# 

9' 

•5" 
22" 
17" 

-,// 
I  '  " 

5' 
12" 

7 
6" 

i'llleis 

1-illeis 

j.iw  plates 

jaw  plates 

Angle  iron  on  roller  i)lates  .     . 

I'ines  of  channels ! 

Hivel  heads 

Spikes 

•            •           • 

Washers 

•           •            •           • 

.         * 

Nuts 

•     • 

.     .     . 

• 

■     ■     ■  1 

'I'olal  weit'ht  of  details      .     . 

19,850 

57.9' 3 

Weight  of  main  portions  .     . 

•       • 

Total  weight  of  iron      .     .     . 

77.763 

1 

i 

I 

nil. I,    OF    LUMIU-.R. 


|oi>ts 

flooring  (e(iuivalent)  .... 

80 

4" 

,4" 

20' 

7.4'''7 

160 

I    ^" 

14' 

6,720 

1  l.iiul  rail  .... 

-•" 

(•)" 

i  l.iiul-rail  |)()sts 

j- 

20' 

040 

34 

4" 

6" 

4' 

Hull  planks 

16 

2" 

tj" 

20' 

640 

Iilly  planks 

'  Ucral  struts 

10 
7 

6" 
7" 

6" 
9" 

20' 
14' 

960 

5'S 

'I'olal  nnnii)er  of  feet,  board 

nieasMri' 

17,214 

156 


OI^D/NAKV  JROX  lllLJllWA  V-H RIDGES. 


Tabic  I.  gives  the  weight  of  iron  per  lineal  foot  of  bridge  as 
479  pounds,  which  multiplied  by  i6o  gives  76,640:  adding  600 
pounds  for  the  spikes,  makes  the  total  weight  of  iron  77,240 
pounds.  This  indicates  an  error  in  the  table  of  only  seven- 
tenths  of  one  per  cent,  — a  very  satisfactory  result. 

If  we  deduct  the  weight  of  the  end  lower  lateral  struts,  roll- 
ers, roller  plates,  anchor  bolts,  etc.,  which  really  do  not  come 
upon  the  bridge,  in  all  about  1,400  pounds,  the  dead  load  per 
lineal  foot  will  be  "^W^'^  +  269  =  746;  which  agrees  within  six 
pounds  with  that  assumed. 

It  may  appear  to  the  reader  who  has  carefully  followed  out 
all  the  calculations  in  this  chapter,  that  the  designing  of  iron 
bridges,  and  estimating  weights  thereof,  involve  a  great  deal  of 
work,  and  demand  considerable  time  :  but  such  is  not  necessarily 
the  case  ;  for  an  expert  could  have  made  this  design  in  from  two 
to  three  hours,  because  his  experience  would  have  told  him  the 
sizes  of  many  of  the  details  and  the  number  of  rivets  to  empiov. 
In  this  chapter  everything  has  been  figured  out  carefully  enough 
for  making  \v'orking-di-awings,  instead  of  merely  an  estimate  of 
weight  ;  foi  the  author  considers  that  it  is  better  to  teach  the 
beginner  oxact  methods  in  the  first  place,  and  leave  him  to 
vlevciop  ipproximate  ones  as  his  practical  experience  increases. 

A  u!-cful  deduction  which  can  be  made  from  the  "  15111  of 
Iron  "  in  this  chapter  is  the  proportion  which  the  weight  of  the 
rivet  lieads  bears  to  the  weight  of  the  rest  of  the  iron,  excluding 
that  of  the  floor  beanis,  spikes,  and  washers.  In  this  case  the 
ratio  is  about  ^^^^(^  =  2.92  per  cent.  The  average  for  a  number 
of  estimates  made  by  the  author  is  2.85  per  cent,  the  greatest 
being  3,  and  the  lfia»t  2.4  per  cent.  The  knowledge  of  this 
fact  will  save  consideiable  time  for  any  one  who  has  many  esti- 
n^a^es  of  weight  to  make. 

The  author  at  «;n(;  time,  when  in  haste,  used  to  figure  out  the 
total  weight  of  ,  jn  portions,  and  divide  by  a  certain  quantity 
less  than  unity,  in  order  to  determine  tiie  total  weight  of  iron, 
but  has  now  abandon*.'!  the  methotl  as  giving  too  loo.sc  an 
ap|/roximation,  finding  that  the  correct  divisor  varies  considera- 
bly with  the  leiigtli  <A  hj)an  and  the  class  o'  bridge.  Tables  1., 
II.,  and  III.  give  the  weights  of  iron  for  all  cases  far  more 
accurately  Ubim  will  *ny  such  apinuxiniation. 


of  brid<ie  as 


ORDINARY  IRON  HIGHWAY-BRIDGES. 


157 


CHAPTER    XVII. 


BRIDGE  LETTIXGS. 

The  ordinary  modus  operandi  of  bridge  Icttings  is  by  no  means 
the  most  perfect  that  could  be  devised. 

A  couple  of  months  before  the  letting,  advertisements  are 
inserted  in  some  of  the  local  newspapers,  stating  that  on  a  cer 
tain  day  at  noon,  in  the  county  town,  at  the  court-house,  there 
will  be  let  the  contract  for  building  a  bridge,  or  several  bridges, 
in  the  county.     The  length  of  span  and  clear  roadway  are  nearly 
ahvays  given;  and  sometimes  this  is  all,  for  the  commissioners, 
as  a  general  rule,  do  not  know  whether  they  want  an  iron  or  a 
combination  bridge.     Sometimes,  even,  they  accept  a  wooden 
oiif  after  advertising  for  an  iron  bridge.     Occasionally  a  very 
fan-  list  of  data  is  advertised,  but  such  is  not  the  rule.     In  addi- 
tion to  the  local  advertisements,  circulars  are  often  sent  to  the 
various  bridge  companies,  requesting  them  to  send  representa- 
tives to  attend  the  letting.     Little  do  the  commissioners  think, 
that  in  the  end  the  county  has  to  pay  the  travelling  e.\i)enses 
of  each   representative  who  attends,  as  well  as  for  his  time. 
Instead,  they  .say,  "The  more,  the  merrier,"  and  congratulate 
themselves  when  they  have  a  good  attendance,  thinking,  that, 
the  nu):e  representatives,  the  greater  the  competition.     It  may 
Ix'  ,su  in  certain  cases  ;  but  ultimately  some  one  has  to  pay  each 
traveller's  expenses,  and  who  but  the  counties  is  there  to  do  it  > 
It  is  true  that  mailed  bids  are  received  :  but  they  are  very  sel- 
dom accepted,  even  if  the  figures  l)e  the  lowest  ;  for  the  commis- 
sioners are  generally  unable  to  resist  the  combined  eloquence 
••f  half  a  dozen  bridge-men.      It  would  be  much  better  for  all 
parties    concerned    if    bids  were   all    sent    by  mail,   and   if  the 
awards  were  made  by  a   competiMit   engineer.      It  would   permit 


i 


,  .A 


'iM'an, 


I  1     r 


!    I 


, 


ii 


IWi 


158 


ORDINARY  IRON  HIGHWAY-BRIDGES. 


of  the  reduction  of  the  staff  of  each  bridge  company,  the  less- 
ening of  cost  to  the  counties,  and,  what  is  more  important,  the 
building  of  better  structures.  When,  by  means  of  much  com- 
petition, the  contract  price  for  a  bridge  is  reduced  to  cost,  or 
even  below  it,  what  does  the  successful  (?)  competitor  generally 
do  ?  Lose  money  ?  Not  at  all  if  he  can  help  it :  that  is  not  his 
way  of  doing  business.  He  puts  up  a  cheap  bridge,  cutting 
down  weight  on  the  details,  and  shaving  as  much  as  he  dare  on 
the  sections.  The  author  does  not  wish  it  to  be  understood 
that  such  is  the  method  of  the  better  class  of  bridge  companies. 
They  generally  know  better  than  to  let  their  travelling  men 
take  contracts  for  nothing ;  and  when  they  do  get  bitten,  as  they 
all  do  occasionally,  they  put  up  the  bridge  at  a  loss,  and  take  it 
out  of  the  next  county  where  they  obtain  a  contract. 

When  remonstrated  with  for  collecting  a  large  crowd  to 
attend  the  letting  of  a  little  bridge,  county  commissioners  have 
been  known  to  respond,  "  You  see,  we  don't  know  exactly  what 
kind  of  a  bridge  would  be  best  for  the  place,  nor  what  style  of 
bridge  the  money  at  our  disposal  will  pay  for  ;  and  when  we  get 
a  lot  of  you  bridge-men  here,  who  know  all  about  it,  we  are  able 
to  find  out  exactly  what  we  need."  Travelling  bridge-men  who 
know  all  about  it !  Bridge  companies  are  not  willing  to  send 
their  engineers  travelling  about  the  country  to  attend  county 
bridge  lettings.  They  cannot  afford  to  pay  for  this  purpose 
salaries  of  two  or  three  thousand  dollars  per  annum,  when  men 
can  be  obtained  to  do  the  work  for  one-third  of  that  amount. 
When  an  engineer  is  found  at  a  bridge  letting,  it  is  generally 
because  he  has  tired  himself  out  at  office-work,  and  needs  a 
little  change. 

It  is  surprising  how  little  the  average  travelling  bridge-man 
really  knows  abo'it  bridges,  and  how  incapable  he  is  of  giving 
advice  of  any  value  to  a  commissioner.  What  he  does  know  is 
how  much  bridges  will  probably  cost,  and  this  knowledge  lie 
obtains  from  the  company's  engineer.  Mis  forte  is  to  do  tlic 
heavy  talking,  in  which  it  is  by  no  means  necessary  for  him  to 
stick  to  the  truth. 

On  the  day  of  the  letting,  four  or  five  honest  farmers  (they 
LUC  honest  usually,  though  there  have  been  and  are  exceptions) 


ORDINARY  IRON  HIGHWAY-BRIDGES. 


159 


mc 


u'ct  to  determine  upon  who  shall  have  the  bridge.  In  some 
cases,  after  the  bids  are  opened,  the  contract  is  immediately  let 
without  discussion,  to  the  lowest  bidder.  At  other  lettings' 
each  company's  representative  is  allowed  to  hold  forth,  in  turn' 
before  the  assembly,  and  show  in  what  way  his  bridge'  is  supe- 
rior to  the  rest. 

Some  of  the  arguments  advanced  are  really  amusino-      One 
will  say  "Mine  is  the  best  bridge,  for  it  has  the  most^ron  in 
the  chords  "  (Ignoring  the  fact  that  his  bridge  has  a  less  depth 
of  truss  than  any  of  the  others).     Another  says,  "  My  bridge  is 
the  best,  because  it  has  the  most  panels ;  and  it  is  an  acknowl- 
edged fact,  that,  the  greater  the  number  of  panels,  the  stron-er 
the  bridge."     Another  will  point  to  the  size  of  his  floor  beams 
forgetting  that  his  bridge  has  one  less  panel  than  have  any  of 
the  others.      With  such  nonsense  are  the  minds  of  the  poor 
commissioners  crammed,  until  they  do  not  know  the  difference 
between  a  cumter  and  a  batter  brace  (in  fact,  it  is  more  than 
probable  that  they  never  did  know) ;  and  the  result  is,  either 
that  the  letting  is  broken  up,  or  that  the  contract  is  let  to  the 
one  who  has  done  the  most  talking,  and  has  impressed  the  most 
lalsehoocis  upon  the  understandings  of  the  honest  farmers. 

Sometimes  the  commissioners  conclude  to  have  the  letting 
done  in  style,  so  engage  the  services  of  an  engineer.  Their 
accjuamtance  with  the  members  of  the  engineering  profession 
being  rather  limited,  they  employ  to  decide  for  them  the  county 
surv  eyor,  whose  technical  knowledge  is  confined  to  the  use  of  the 
compass  and  transit,  and  whose  mathematical  education  never 
went  much  farther  than  arithmetic.  Or  perhaps  taey  will  find 
some  one  much  looked  up  to  in  the  county  as  an  engineer,  who 
iias  been  plucked  at  some  technical  school,  and  returned  home 
t«>  enjoy  the  honors  of  having  been  a  college-man. 

As  Professor  Vose,  not  long  ago.  stated  in  a  very  able  article 
luihlishcd  in  the  "Journal  of  the  Association  of  Engineerin<. 
Societies  ••  and  "Van  Nostrand's  Mag.^irH.."  in  -r.ier  to  insure 
the  l)u,l,i,ng  of  none  but  good  bridges,  there  miust  be  a  State 
■nspector,  whose  duty  it  would  be  to  pass  iii<lgment  on  the 
Pl.nis  <.f  all  bridges,  before  p.Tn,itting  them  to  be  erected  in 
'-K'  State.     Such  an  inspedor  should  be,  not  an  ordinary  en-i- 


i6o 


(V^nrxANv  //c(hv  iiighway-bridges. 


neer,  but  an  expert  in  bridge  designing.  He  should  receive  a 
handsome  salary,  and  be  allowed  enough  assistance  to  enable 
him  to  do  his  work  in  a  satisfactory  and  efficient  manner.  His 
ter.ure  of  office  should  be  for  life,  or  for  a  long  term  of  years, 
and  should  be  beyond  the  reach  of  politics  and  politicians.  As 
long  as  his  work  be  done  efficiently,  his  position  should  be 
assured  to  him  ;  for  a  man  of  the  requisite  experience  and  ability 
would  not  be  willing  to  accept  the  position  under  other  condi- 
tions. 

The  letting  of  bridge  contracts  to  the  lowest  bidder  is  the 
worst  method  that  could  be  adopted,  even  when  plans  and 
specifications  are  on  file  ;  for  the  work  generally  goes  to  the  most 
unscrupulous  bidder,  who  will  secure  his  margin  of  profit  by 
diminishing  the  weight  of  the  details.  This  weight  should  be 
about  twenty-five  per  cent  of  the  total  weight  of  iron-work  in 
the  bridge,  and  it  is  quite  possible  to  reduce  it  to  one-half  of  this 
amount. 

If  ignorant  commissioners  must  have  a  rule  for  letting,  it 
would  be  better  to  award  the  contract  to  the  highest  bidder. 
But  the  proper  way  would  be  to  engage  the  services  of  a  man 
who  knows  something  about  bridge  construction,  and  have  him 
figure  out  the  probable  cost  of  the  bridge,  allowing  a  fair  margin 
for  profit.  A  margin  of  from  fifteen  to  twenty  per  cent  is  not 
excessive,  even  upon  a  liberal  estimate  of  cost ;  for  such  a 
margin  by  no  means  represents  the  contractor's  actual  profits. 
From  it  must  be  subtracted,  not  only  a  portion  of  the  annual 
office  expenses,  including  salaries  of  clerks,  draughtsmen,  and 
engineers,  but  also  the  bidding  expenses  of  several  lettings 
where  the  contractor  has  been  unsuccessful.  Then,  too,  there 
is  the  risk  of  bad  weather,  high  water,  rise  in  ])rice  of  iron, 
delay  in  shop,  etc.,  any  one  of  which  is  liable  to  absorb  the 
whole  calculated  profit,  to  say  nothing  of  the  liability  of  losing 
the  bridge  by  a  freshet  during  erection. 

When  the  appropriation  is  small,  it  is  much  better  to  build 
a  good  combination  bridge  than  a  poor  iron  one,  because  the 
wood-work  of  the  former  can  be  replaced  when  it  wears  out  ; 
while  the  iron,  if  properly  cared  for,  is  as  good  as  new.  Hut  a 
used-up  iron  bridge  is  worth  little  more  than  the  cost  of  taking; 


OA'DJXA/n-  /A'O.V  JIIGIIWAY-BIUDGES.  .Cn 

il^^'l-^vn,  and  transporting-  it  to  where  it  can  be  sold   for  old 

TiK.   method   of  having  plans  and   specifications  on  file  for 
cv.ry  competitor  to  bid  upon  is  not  a  good  one.     In  the  firs 
1  ace.  .t  necessitates  the  sending  of  engineers  to  the  letting,  or 
at  Ic  St      ose  who  are  capable  of  figuring  out  the  weight  of  a 
bndge,  thus  greatly  increasing  the  bidding-expense  •    then    i 
the  p  ans  are  at  all  defective  in  design,  a  fi;;t.cL     om^ 
-nvdhng  to   b.d   upon   them.     It   is  much  better  to  let  elc 
company  bid  upon  its  own  designs 

V^  most  city  bridges  and  for  very  large  county  bridges,  it  is 
-  h  a  bridge  company's  trouble  to  prepare  special  dL  n^s  • 
'-t.lor  ordinary  county  lettings.  standard  drawings  will  ansvt  .' 
^ciy  purpose  when  accompanied  by  a  diagram  of  stresses  and 
special  specifications.  If  the  letting  is  to  be  done  by  an  e.vd 
ncer.  a  plate  of  details  similar  to  Plate  III.  or  Plate  IV.  will  Se 
uf  cient    but  the  ordinary  county  commissioner  does  not  u   der 

<:r   ih        s"f  '""""^-  ^^^"^^  ^^  ^-  -hat  the  bridge 
^^'11    ook  like.     Such  a  picture  as  the  one  given  on   Plate   I 
would  be  very  taking  with  county  comnussio^ers.  but  thJ  e    s 

..rea   dea   of  labor  involved  in  making  such  a  drawing.     As 
.general    rule,   a    sheet    showing  side  and  end  elevati.ms    an 
a  plan  of  either  the  whole  or  one-half  of  the  bridge,  will  b  's 
uot  when  supplemented  by  a  sheet  of  details 

It  IS  nut  unusual  for  a  fancy  drawing  to  take  a  contract  when 
thcic  are  much  better  and  even  cheaper  structures  in  com,;:;;: 
^  JhyHagram   of   stresses  should  be  filled  out  as  shown  on 

Specifications  should  be  quite  e.vplicit  without  bein<^  Ion-    o, 
-"  -ing  to  a   reader  of  o,-dinary  intelligence.      The     uTh 
-u  1  recommend  the  following  or  some  similar  form  of 


J  6: 


OND/XAKY   /A'OA'  HIC.UWA  V-ltRlDuES. 


SMITH    &   WILLIAMS, 
BRIDGE   ENGINEERS  AND   BUILDERS, 

PITTSBURGH,  PENN. 


SI'FXIFICATIONS  FOR   BUILDING   A  WROUGHT-IRON   HIGHWAY-BRIDGE. 


ri 


Length  of  Span.  —  To   be feet inches  between  centres 

t  end  pins 
bearings. 

Clear  Roadway.  —  To  be  feet nclies  between  innermost 

portions  of  trusses. 

Live  Load.  — To  be  pounds  per  lineal  foot  of  bridge. 

Dead  Load.  — To  be  pounds  per  lineal  foot  of  bridge. 

Depth  of  Truss.  — To  be    feet   inches   between   centre 

lines  of  chords. 


Clear  Headway.  — To  be  feet 

lowest  part  of  overhead  bracing. 


inches  between  floor  am 


Upper  Chords  and  Batter  Braces.  — To  consist  of  two  inch  ch;in- 

uels,  with  a  plate  inch  by  inches  above,  and  lattice 

bars  inch  by  inches,  riveted  together  at  tiieir  mid- 

flle  points,  below. 

Splicing  of  Joints  in  Upper  Chords.  —  Sliall  be  madr  l)y  a  jjlate  on  e:i(  li 
side,  as  shown  in  the  accompanying  draw int,^  Tiiesc  plates  shall  lie 
of  such  thickness  as  to  atford  sufficient  iiearing  for  tlic  pins,  and  tluir 
combined  sectional  area  siiall  not  be  less  than  that  of  the  ciiannels 
which  they  connect.  Xo  splice  plate  to  be  less  than  three-eighths  i  J) 
of  an  inch  in  thickness.  These  connections  shall  be  designed  •■■"' 
the  supiiosition  tliat  the  entire  stress  is  carried  by  the  jjlate 
rivets,  no  reliance  being  placed  on  abutting  ends  of  channels. 

Cover  Plates  for  Choi  Js.  —  Shall   be  inch   by  inches  ! 

inches,  and  sliall  contain  a^  many  rivets  on  each  side  of  ■'- 

joint  as  will  suffice  t"  carry  tiie  i;reatesL  stress   tha:  cm   ever  cnnic 
upon  tile  chord  plates. 


iiii'!i  r 
s   ami 


JHWAY-BRIDGE. 


between  centres 


tween  innermost 


between   centre 


ctween  floor  anil 


( >a-/j/a:ia- i -  /A'OA-  iiuiiiu  -,/  J '-nA'/ih;Ks.  163 

i'ticI)  by 


Stay  Plates  for  Chords  and   Batter  Braces.  —  Shall   be 

inches. 


Posts.  -  Shall  consist  of  two  ciiannels,  of  sizes  as  marked  on  the  accompanv- 
ing  diagram  of  stresses.    The  latticing  for  same  shall  vary  from 

;"*:''  ''^:     , ,■, 7'^*^^  J-^ ^^^^  ^y inches;  the'bar; 

bemg  riveted  together  where  they  cross  each  other.  The  posts  are  to 
be  attached  at  their  ends  to  the  chord  pins,  an<l  are  proportioned  for 
both  ends  hmj,a.d.  At  the  upper  ends  the  connections  are  to  be  made 
by  extension  plates,  each  of  which  is  to  have  a  sectional  area  between 
the  pin  hole  and  stay  plate  equal  to  twice  that  of  the  channel  to  which 
It  isattached.  The  entire  stress  in  the  posts  is  to  be  considered  as 
c.-irried  by  the  extension  plates  and  their  rivets,  no  reliance  being 
|.laced  on  abutting  ends  of  channels. 

Upper  Lateral  Struts.  -  Shall    consist   of  two  channels,     ''''?"'      of   sizes 
,       ,  latticed, 

given   on   the   diagram   of  stresses,  rigidly  attached  to  the  chord. 

lacing 
^  '''■■  lattice  '''^'■''   f"""  ^'T"*-'  •'^liall  vary  in  section  from  

^^: ,; /"'^•'^^  '°  i"^l>   by  inches;   and   the 

.stay  plates,  from  inch    by    inches   by 

'"'^''^^  '« inch  by inches  by  ..  inches 


s. 
inch 


Portal  Bracing  (at  each   end   of   the 

o  

laced 


one 


i  span).  —  Shall  consist  of   ,        struts 

,  ,     ,  two     "•'"'^=>» 

each  composed  of  two  inch  channels,  as  marked  on   the 


diagram   of  stresses,  ,^^^.^^^,  „y   „ars    i„ch    by   

inches  in  .section,  with  stay  plates  inch   by inches 

b>' inches;  also  lour  adjustable  rods,  each  inches 

m  diameter.     The  struts  are   to   be  rigid.-    atached   to   the   batter 
i)races. 

Vertical  Sway  Bracing(between  posts).  -  Shall  consist  of  two  vibration  rods, 

^■^'-■''  '"ch  in  diameter,  and  an  intermetliate  strut  of 

inch  I-beam,  weighing  pounds  per  foot,  rigidlv  attached  to 

t..e  posts  at  a  distance  of  feet  inches   below  the 

level  ot  the  upper  chord  pins. 

End  Lower  Lateral  Struts.  -  Shall  consist  of  


Intermediate  Lower  Lateral  Struts. -Shall   consist  of  inch   l,v 

inch  pine  timber,  lying  upon  the  Moor  beams,  and  well  bolted 
thereto,  and  attached  by  vsrought  iron  jaws  to  the  chord  pins. 


•  I 


ir,4 


oN/u.y.ih'v  /A'ox  iiminvA  v-i'>Riin;i-:s. 


Side  Bracing.  —  Sliall  (onsist  of  indi  liy  inch  

pound  angle  iron,  well  rivitcd  to  the  t(>|)  iliord  and  to  tlii'  lluor  lu-ams. 
whicli  ari'  prolonged  feet  inches  at  eaeli  end  be- 

yond tiie  trusses  for  this  purpose,  as  shown  on   the  aecomimnying 
drawing. 

Bottom  Chords.  —  .Shall  consist  of  eye  bars,  as  marked  on  the  di.igrani  of 
.stresses,  tliose  in  the  two  panels  next  to  each  end  of  the  span  being 
trussed. 


Main  Diagonals.  —  Shall  consist  of  eye  bars  of  the  sections  marked  on  the 
diagram  of  stresses. 

Counters. —  .Sh.dl  consist  of  adjustable  rods  with  loop   eyes,  the  sections 
being  as  irarked  on  the  diagram  of  stresses. 

Upper  Lateral  Rods.  —  Shall   be   from    inch   to  inches 

round  iron,  attached  by  bent  eyes  to  the  chord  pins. 

Lower  Lateral  Rods. —  Shall  be   from    inch  to  inches 

round  iron,  attached  eithcf  to  the  chord  pins  by  bent  eyes,  or  to  special 
pins  passing  tiuougli  the  lateral  strut  jaws  i)y  loop  eyes. 


Floor  Beams. 


Shall    be 


rolled 
iiuilt 


licanis   inches   dee]),   weighing 

pounils    per   lineal    toot;  web         inch    by 

inches;  ujiper  llanges.  two  inch  by  inch   

pound   angles;    lower  llanges,   two   inch   by    inch 

pound  anulcs.     Stillencrs  to  be  of  inch  by 

inch  .  pound  angles,  jier  beam,  niaele  tiush  with  the 

vertical  legs  of  the  Hange  angles  by  liHing-i)lates. 


Beam  Hangers.  —  Are    to    be    of 

four 


I'ountl  upset 

inch    iron. 


sciuar." 


not  upset: 


there  are  to  be     ^^.^^  of  them  to  cacli  beam. 


Beam-Hanger  Plates.—  Are  to  be inch  by inches  by. 


men 


Shoe  and  Roller  Plates.  —  Are  to  be   inches 


thick. 


Pins.  —  Are  to  be  of  the  sizes  marked  on  tlie  diagram  of  stresses.    They  shall 
be  turned  so  as  to  tit  the  pui  holes  within  one-liftieth  (jl,,)  of  an  inch. 

Pin  Bearings.  —  .All  jjin  bearings  ;ue  to  be  properly  re-entorced. 


;  niaikfd  on  tlic 


."s,  tlie   sections 


ORDIXARV  IROX  IIIGHIVA  V-IIIUDGES. 


1^5 


Brackets.  -  A  straight  bracket  of i,„h  by  inch 

pound  an  :le  iron  is  to  l,e  used  to  connect  each  post  to  tl,e  overhead 

strut.     Ihoseforthf  portals  are  to  he  ot  inch  l.v 

'"L-h    pound  


rivets  at  cacli  lik 


ui.i,'lc   iron      The) 


be   connected  by 


Chord  Heads.  -  .Shall  be  of  standard  shapes,  and  so  strong  that  the  bar  will 
l.icak  in  the  body  rather  than  in  the  neighborhood  of  the  eye. 

Upset  Rods.- Ail  adjustable  rods,  unless  otherwise  specified.         ,o  have 
heir  ends  .  Hiarged  for  the  screw  threads;  so  that  the  dian.eter  at  the 

h     'll' .;  of  .T    l"T'  ff  1"  ""•^--^'-■"'"  ^'«^  ^'f  -'   -ch  greater 
tl  an  that  .,f  the  body  of  the  bar,  scjuare  or  Hat  bars  being  figured  as  if 

of  ecjuivarnt  round  section. 

Riveting  -Riveting  shall  in  every  respect  be  in  accordance  with  standard 
authonties;  and  all  riveted  connections  shall  be  designed  for  he 
nvets  to  resist  the  greatest  shearing,  bearing,  and  bending  stresses 

Expansion.  _  .Shall  be  provided  for  by  . 


Anchorage. -At  one  end  of  ^^^^   .sp,n,  the  superstructure   is   to   be  an- 
chored to  the   foundations  by bolts,  each  inches 

'"  •"'^""^'^'•'  =^"''  ^'  l^^^t  feet inches  long! 

Ca.be.      Shall  be  at  least finches  when  the  bridge  is  empty,  and 

'"  '^-'^^  "iches  when  fully  loaded. 

'"°"'  ^""'Tiir  ^'''"  ™"""  "^  '""'  "^ '"'^'^  by 

i'Hh  ,,^^,^   joists,  dai)ped  and  spiked  on  the  lateral  struts;  and  the 
lloor  plank  shall  be  of_  i„ch  pine  or  oak  plank  laid  diago- 


nally  or  square  across  the  bridge,  as  may  be  preferred,  and  well  spiS" 
1"  •''^;  J"'-^'-^-     ^  f^'lly  plank  of inch  by    .  ,„ ch  nine 


Hand  Railing.  —  To  consist  of 


^ 


.0^.  "'>.^; 


IMAGE  EVALUATION 
TEST  TARGET  (MT-3) 


1.0 


I.I 


u 


IM 


2.5 
2.2 


^    IAS    IlilM 


1.8 


1.25 

1.4      1.6 

♦ 6"     

»k 

V] 


<^ 


/^ 


/. 


>!^ 


^^^ 


# 


Photographic 

Sciences 
Corporation 


23  WEST  MAIN  STREET 

WEBSTER,  N.Y.  14580 

(716)  872-4503 


i 


!l 


1 66 


OIWfNARV  IROA-   HIGHWAY-BRIDGES. 


Details  of  Construction.  — All  details  of  construction  to  lie  i)ropcily  pro 
portioned  with  clue  regard  to  the  various  direct  and  indirect  stresses 
that  may  come  upon  them.  All  joints  to  he  machine  dressed  and  to 
fit  perfectly.  Riveting  in  the  field  to  be  performed  in  a  skilful  man- 
ner, using  the  button  set.  There  shall  be  no  loose  rivets  in  the 
bridge. 

Quality  of   Materials.  —  Iron   for  tension   members  to  have   an  ultimate 

strength  of pounds  per  square  inch,  and  an  elastic  limit  of 

pounds  per  square  inch.     Iron  for  compression  members  to 

have  the  usual  correspondence  of  strength.     All  timber  to  be  sound 
and  of  good  quality. 

Workmanship.  —  All  workmanship  to  be  first  class  in  every  respect,  and  to 
be  performed  to  the  satisfaction  of  the  engineer  or  commissioner  in 


charge. 


.,  1 88 


(Signed) 


SMITH  &  WILLIAMS. 


With  the  diagrams  of  stresses,  plans,  and  specifications,  there 
should  be  handed  in,  or  sent  to  the  commissioner,  a  proposal  in 
the  following  or  some  similar  form  :  — 


To  the  County  Commissioners  of County, 

State  of 


Gentlemen,  —  We  the  undersigned  hereby  agree  to  build,  and  put  in  con- 
dition for  travel,  the  superstructure  of  an  iron  highway-bridge  of 

spans,  across  '  i"  "i<=  bounty 

of ,  State  of .according 

to  accompanying  plans  and  specifications,  for  the  sum  of 

dollars cents  ($  ). 

SMITH  &  WILLIAMS, 
,  1 88. 


After  the  contract  has  been  awarded,  the  successful  com- 
petitor and  the  commissioners  must  sign  it,  and  a  bond  must 
generally  be  given  by  the  company  as  a  guaranty  that  they  will 
complete  the  work  according  to  the  specifications.  It  is  well 
for  the  representative  of  each   company  to  be   provided  with 


ORDLYARV  /A'ChV  HIGHHA  V-IUUDGES. 

l)lank  forms  for  contract  and  bond.     The  author  would 
mend  the  following  for  this  purpose  :  — 


167 


recom- 


:T 


BRIDGE  CONTRACT. 


&  WILLIAMS. 


\   &  WILLIAMS. 


This  Agreement,  made  and  entered  into  this 


nt 

lifiilijL'  hii 
th 


day 


:t;:::Z--^^:--^^^ 


Count}-  of c»   »        r 

•'       ,  State  of 

parties  of  the  second  part, 

Witncsseth  That  the  said  narties  of  thp  five        .  1 


of  a 

bridge 

across  

>  in   said  county, 





-'':;,:;*Y,',i;: :''""'' """ '---  -  ';-„f  *---  '■■■■ 

l»i<k.  a,     a.         '  ,  °.  "  ,"'  '""■'.'""'■'  •i''!"""'  '!"■  '"alcrial  tor  safd 


of 


ItndL^c  CO 
A.[).  iSS 


I'll: 


Mi' 


l68  ORDIXARY  IROX  HIGHWAY-BRIDGES. 

part  contract,  and  agree  to  pay  to  tlie  said  parties  of  the  first  part  tlie  sum  of 
dollars,  payable  as  follows : 

///  witness  whereof  the  said  parties  do  hereunto  affix  their  seals  and 
signatures  the  day  and  year  above  written. 

L^I^AL.]  

[seal.]  

[seal.]  

[seal.]  


BOND   FOR   BRIDGE   CONTRACT. 


Know  all  men  by  these  presents,  That  we.  Smith  &  Williams  of  Pitts- 
burgh, I'enn.,  as  principals,  and 

as  sureties,  are  held  and  firmly  bound  to  the 

in  the  State  of in  the  penal  sum  of 

dollars,  for  the  payment  of  which,  well  and  truly  to  be  made,  we  bind  our- 
selves, our  heirs,  executors,  administrators,  and  assigns,  jointly  and  severally, 
firmly  by  these  presents. 

Dated  at in  the  County  of 

and  State  of  this day  of ,  i88 

The  condition  of  this  obligation  is  such,  that  if  the  said  Smith  ilv: 
Williams  construct  bridge  in  the  aforesaid  county,  according 
to  llie  plans,  specifications,  and  contract  hereto  attached 


tlien  this  obligation  to  be  void  and  of  no  effect,  or  otherwise  to  remain  in 
full  force  and  virtue  in  law. 

Principals. 


Sureties. 


ix  their  seals  and 


ViLLIAMS  of  Pitts- 


ORDINA  R  Y  IROX  HlGmVA  Y-liRlDCl-S.  1 69 

The  previous  remarks  concerning  methods  of  bridge  lettin-s 
w.ll   probably  not   be  altogether  approved  of    by  contractor! 
Mr    A.   I.    Boiler,  C.K.,   in   his    treatise   on   "Iron    Highway- 
Bridges,    writes,  '<  It  will  be  noticed  in  the  last  clause  of  the 
lorin  for  'Invitation.'  bidders  are  requested  to  be  present  at 
the  opening  of  the  bids,  and  hearing  them  read.     This  is  simple 
just.ce.     And  when  one  considers  the  time  required  to  make 
plans  and  estmiates,  even  for  a  small   piece  of  work,   to   say 
noticing   of    the  expenditure  of  money  incident  thereto    with 
l-robable   travelling-expenses  in  addition,  no  fair-minded    man 
can  object  to  rendering  at  least  what  satisfaction  may  be  derived 
tn.m  the  public    opening   of   tenders.      Bids   secretly  opened 
always  lead,   whether  justly  or  unjustly,   to  the  suspicion   of 
unfair  practices,  an  imputation  that  can  be  readily  removed  by 
inc  method   of  publicity  suggested,   a  method   which   can   be 
()I)jected  to  by  no  one.  unless  those  whose  mode  of  doin-  busi- 
ness seeks  darkness  rather  than  light."      This  is  a  clear  and 
well-stated   argument,  and  it  is  difficult  to  propose  a  method 
that  will  overcome  every  objection  advanced.     ii„vvever  there 
are  some  points  in  it  that  will  bear  criticising. 

iM.r  a  bridge  worth,  say,  twenty  thousand  dollars,  all   that 
Mr.  Bo  ler  says  is  certainly  correct.     But  is  it  so  for  a  small 
c.nmty  bridge  ?     The  majority  o.  county  bridges  do  not  exceed 
unc  hundred  feet  in  length,  and  they  are  very  often  let  sino-ly 
How  long  wdl  it  take,   in  a  well-regulated   office,  to  preplire 
plans  and  estimates  for  an   ordinary  one  hundred-foot  county 
hndge.      Usually  about   thirty  minutes;  at  any  rate,  no  more 
tnan  two  or  three  hours.     The  work  consists  in  taking  out  of 
their  proper  places  a  blue  print  of  the  diagram  of  stresses  a 
sheet  of  details,  a  general  plan,  and  blank  forms  of  specification 
and  pn.po.sal,  then  filling  out  the  two  latter,  and  enclosin-  all 
'"  an  envelope  for  the  post.     The  making  out  of  the  estimate 
ot  cost  should  not  take  five  minutes  when  the  amounts  of  iron 
a"'l  lumber,  and  a  complete  list  of  data,  are  at  hand      If  the 
span   be  of   unusual   length,  as  sometimes    happens  when   re- 
])lacing  an  old  structure,  it  may  be  necessary  to  make  out  a 
new  diagram  of  stresses,  but  not  to  prepare  a  bill  of  material  • 
t"i-  every  bridge  company  should  have  tables  of  weights  of  iron' 


I 


170  OJaJJ.XAKV  /A'OX  JlIGIIWAY-IiRIDGES. 

and  amounts  of  lumber,  for  all  ordinary  cases.  The  actual 
cost  to  the  contractor,  of  an  ordinary  county  bridge  of  one 
hundred  feet  span  and  sixteen  feet  clear  roadway,  can  be  seeii 
from  the  following  estimate  :  — 

Wrouiilit-iron,  27,900  lbs.  at  5c 5l>39S  00 

Lumlier,  io,8<So  ft.  at  #18  per  M '95  84 

Haulinj.j,  20  loads,  at  $1.50 30  00 

Framing 7  00 

Falsework 25  00 

Erection 1 50  00 

Paintinij; 25  00 

Blacksmi thing 5  00 

Coal 2  00 

Frcii^ht  on  tools 15  00 

Travellin<:;-expcnscs 30  00 

Men's  time  travelling 20  00 

Bidding-ex])enses 40  00 

Teaming  during  construction lo  00 

Incidentals 50  00 

Total  cost  of  bridge f  1,999  ■'^4 

Cost  per  lineal  foot,  say 20  00 


Adding  twenty  per  cent  for  profit  would  make  the  bridge 
cost  the  county  $2,400.  Now,  suppose  there  are  ten  other 
bidders  present,  each  of  whose  expense  for  time  and  travelling 
is  forty  dollars ;  then  there  will  be  an  additional  four  hundred 
dollars  to  be  added  to  the  cost  of  this  or  some  other  bridge, 
for,  as  before  stated,  some  one  must  pay  it.  Kleven  is  by  no 
means  an  unusual  number  of  bidders  for  a  small  span  :  there 
are  often  as  many  as  fifteen  or  sixteen. 

The  estimate  for  forty  dollars  for  time  and  travelling-expenses 
is  not  excessive,  as  the  author,  who  has  attended  a  number  of 
lettings,  can  testify. 

These  four  hundred  dollars  are  worth  saving,  if  it  can  be 
done  legitimately. 

As  for  bids  secretly  opened  always  leading  to  the  suspicion 
of  unfair  practices,  it  is  indeed  true  ;  and  there  is  no  way  of 
avoiding  the  difificulty,  except  by  having  them  opened  by  a  com- 
mittee of  public  men  who  are  above  suspicion.     These  could  bo 


'J£S. 


ORDINARY  [RON  HIGmVAY-IiRlDGES. 


I/I 


. 

The  actual 

bridge   of  one 

y,  can  be  seen 

•  ?i,39S  oo 

•  95  84 

30  00 

7  00 

25  00 

150  00 

25  00 

5  00 

2  00 

15  00 

30  00 

20  00 

40  00 

10  00 

50  00 

i?i,999  '"^4 

20  00 

ake  the  bridge 

are  ten    otlicr 

and  travelling 

1  four  hundred 

t  other  bridge, 

leven  is  by  no 

ill 

span  :  there 

elling-expenses 
d  a  number  df 

g,  if  it  can  be 


government  employees,  and  residents  of  the  capital  of  the  State, 
to  which  bids  for  all  county  bridges  should  be  sent.  Ihe  duty 
of  the  committee  would  be  merely  the  opening  of  the  bids,  and 
the  recording  of  the  amounts.  The  inspector  of  bridges,  who 
should  also  reside  in  the  capital,  should  then  examine  the  bids, 
and  report  to  the  county  commissioners,  which,  in  his  opinion,' 
is  the  best  bridge  for  the  money  (i.e.,  which  he  would  advise 
tlnm  to  accept),  and  which  bridges  arc  up  to  the  specifications, 
and  which  not,  leaving  the  final  decision  to  the  commissioners. 

A  summary  of  his  report  should  be  advertised  in  certain  of 
the  engineering.papers,  say  the  two  which  have  the  greatest 
circulation,  so  as  to  let  the  public  see  that  there  has  been  fair 
play,  and  to  clear  the  inspector  of  any  imputation  of  unfair  prac- 
tice. The  advertising  of  the  report,  including  the  price  for  each 
bridge  and  the  estimated  weight  of  iron  in  same,  would  serve 
to  prevent  any  connivance  between  contractors  and  commis- 
sioners;  because  any  decided  departure  from  the  recommenda- 
tion of  the  inspector  would  immediately  awaken  suspicion. 

No  bids  without  an  estimated  weight  of  iron  should  be 
received  ;  and,  should  the  inspector  doubt  the  genuineness  of 
the  estimate,  he  could  easily  check  it. 

Then,  too,  the  bridge  should  be  weighed  at  the  railway  sta- 
tion nearest  the  site ;  and,  if  the  weight  be  found  wanting  more 
than  a  certain  per  cent  of  the  estimated  amount,  the  contractor 
.should  be  fined. 

\\\  this  way  the  only  possibility  of  fraud  would  be  an  agree- 
ment between  a  certain  bridge  company  and  all  the  mem"bers 
of  the  committee  for  the  latter  to  insert  the  contract  price  in 
their  hid  .so  as  to  make  it  just  a  little  lower  than  that  of  any 
other  competitor.  Considering  that  the  committee  would  be 
composed  of  a  number  of  the  most  prominent  state  officials,  the 
I)robability  of  such  a  fraud  ever  occurring  reduces  to  zero. 


i 


•  the  suspicion 
e  is  no  way  of 
lened  by  a  com- 
These  could  be 


\72 


ORDIA'ARY  ]R0,\  IHCllU-AV-nKIDCES 


CHAPTER  XVIII. 


WORKING-DRAWINGS. 


I  III 


The  first  points  to  be  determined  before  commencing  a  work- 
ing-drawing are  the  scale  and  the  size  of  the  paper.  The  least 
scale  which  it  is  convenient  to  use  is  one  inch  to  the  foot,  and 
the  greatest  scale  for  a  whole  drawing  should  seldom  exceed  an 
inch  and  a  half  to  the  foot.  If  a  smaller  scale  than  one  inch 
be  used,  difficulty  will  be  experienced  in  writing  the  rivet  spacin"- 
between  the  rivet  holes.  The  width  of  the  i)apcr  should  be  from 
three  and  a  half  to  four  and  a  half,  or  ever  five  feet :  and,  as 
for  the  length,  it  is  better  to  use  roll-paper,  and  not  to  cut  it 
until  the  limits  of  the  drawing  be  determined  ;  for  it  is  a  great 
convenience  to  be  able  to  make  ajl  the  working-drawings  for  a 
bridge  upon  a  single  sheet 

The  following  is  a  draughtsman's  equipment  for  making 
working-drawings  in  a  methodical  and  expeditious  manner  :  a 
table  from  four  to  five  feet  wide,  from  six  to  eight  feet  long, 
and  about  three  feet  high  ;  a  pair  of  steps  each  three  or  four 
inches  rise,  and  three  feet  long  ;  a  bevelled  steel  straight-edge,  at 
least  three  feet  long  ;  a  beam  compass  with  tangent  screw  attach- 
ment ;  a  couple  of  small  triangles  (rubber  ones  are  the  best); 
some  four-H  and  six-H  pencils  ;  a  little  tracing-paper  ;  a  finely 
divided  duodecimal  boxwood  scale  (the  subdivisions  being  quar- 
ters, eighths,  and  sixteenths);  a  good  box  of  instruments,  includ- 
ing a  protractor  and  a  pair  of  hairspring  dividers  ;  and  the  usual 
outfit  of  rubbers,  tiles,  pens,  etc.,  that  one  finds  in  draughts- 
men's ofifices.  T-squares,  large  triangles,  and  parallel  rulers 
should  never  be  used  in  making  a  working-drawing.  The  first 
can  never  be  depended  upon,  because  of  the  impossibility  of 
having    both    board    and    T-square    always    perfectly  true ;    no 


ORDLVARV  f/w.V  HIGHWAV-BRIDGES.  xy^^ 

wooden  ruler  can  be  relied  on  not  to  warp ;  and  parallel  rulers 
are  a  delusion. 

I'or  a  few  inches  it  is  permissible  to  turn   rioht  angles  with 
truin-les,  but  for  Ion-  distances  the  beam  compass  should  be 
used  ;  and  parallel  lines  can  be  most  accurately  drawn  by  erect- 
in-  a  perpendicular  near  each   end   of  the  original  line,   and 
laying  oif  on  them  equal  distances.     When  distances  are  a  little 
too  great  for  the  triangles,  and  too  small  for  the  beam  compass 
the  large  ordmary  compasses  can  be  used  ;  but  it  will  be  founcl 
that  they  are  seldom  required.     The  four-II  pencils  are  to  be 
iise.l  for  writing  dimensions,  etc.,  and  the  si.x-H  ones  for  draw- 
ing I'lies.     The  draughtsman  should  always  have  at  least  one 
ot  the  latter  sharpened  to  a  chisel  edge  for  ruling,  and  another 
to  a  point  for  sketching.     He  will  find  it  to  be  greatly  to  his 
advantage  to  keep  his  pencils  always  well   sharpened,  for  an 
error  ot  the  width  of  a  pencil-line  will  often  cause  a  great  deal 
of  inconvenience.     A  piece  of  emery  paper  or  a  fine  file  will  be 
ound  useful  for  sharpening  pencils.      The   tracing-paper  will 
be  convenient  in  transferring  drawings  of  similar  chord  heads 
etc.  :  Its  function  is  merely  the  .saving  of  a  little  time 

It  is  generally  better  to  have  both  a  long  and  a  short  scale 
The  long  one  may  be  divided  into  feet  only,  the  inches  and  frac- 
tions of  inches  being  taken  from  a  diagonal  or  other  small  scale 
If  the  draughtsman  be  not  provided  with  a  suitable  scale  he 
can  easily  prepare  a  very  fair  one  for  himself  on  a  strip  ot  the 
roll  of  paper  upon  which  the  drawing  is  to  be  made. 

The  method  of  projecting  one  view  of  a  piece  from  another 
now  will  not  do  for  working-drawings.  owing  to  the  liabilitv  of 
the  triangles  to  slip.  All  measurements  should  be  transferred 
by  the  dividers  ;  and,  if  there  be  any  probabilitv  of  the  points  of 
the  dividers  having  been  moved,  the  distance  between  them 
■should  be  tested  by  laying  it  off  once  more  upon  the  original 
length.  There  should  be  no  more  than  a  single  transferrence 
of  any  one  distance,  for  errors  often  increase,  instead  of  bal- 
ancing. 

The  general  arrangement  of  a  working-drawing  consists 
merely  in  laying  out  a  plan  and  elevation  of  one-half  of  the 
span,  leaving  at  least  a  foot  of  space  at  each  end,  and  six  or 


a  KH  na  fin 


174 


ORD/XAKV  IROX  HIGHWAY-BRIDGES. 


1  i  I  J'i 


itiii 


I  ■ . , 


Hi 


eight  inches  above  the  elevation  and  below  the  plan,  if  there  be 
room  to  spare,  with  the  same  distance,  or  a  little  more,  between. 
As  it  is  immaterial  if  different  portions  of  the  drawing  cross 
each  other,  provided  that  such  intersection  cause  no  conflictini,^ 
of  the  measurements,  the  various  members  may  be  shown  in 
several  \iews  alongside  of  their  respective  positions  in  plan  and 
elevation. 

Thus  the  top  chord  may  be  represented  in  an  under  and  an 
upper  view  above  the  elevation  of  the  truss,  and  the  batter 
brace  may  be  shown  in  a  similar  manner  above  and  to  one  side 
of  the  elevation.  Projections  of  the  posts  on  planes  transverse 
to  the  bridge  may  be  drawn  alongside  and  a  little  below  the 
elevation  of  these  members,  the  amount  of  lowering  beini;- 
sufficient  to  bring  the  ends  of  the  strut  clear  of  the  chords. 
Attached  to  the  projections  of  the  posts  can  be  shown  the  inter- 
mediate struts  and  vibration  rods,  with  their  connections ;  antl 
shortened  views  of  the  chord  bars  and  diagonals  can  be  placed 
alongside  their  elevations  in  order  to  represent  the  heads  clear 
of  all  other  members.  Passing  to  the  plan,  on  one  side  is  drawn 
the  packed  lower  chord,  and  attached  thereto  the  lower  lateral 
rods  and  struts  in  half-length  ;  while  alongside  the  latter  can  be 
represented  an  elevation  of  the  same  with  the  floor  beams 
beneath,  and  an  end  view  of  the  beams  near  by.  At  the  other 
side  of  the  plan,  can  be  shown  half-lengths  of  the  upper  lateral 
rods  and  struts  in  two  views,  and  a  projection  of  the  portal 
bracing  on  the  plane  of  the  batter  braces,  and  on  planes  at  right 
angles  thereto.  Each  detail  can  be  delineated  to  any  required 
extent  in  the  neighborhood  of  its  position  in  plan,  elevation,  or 
both.  If  necessary,  the  panel  points  on  one  side  of  the  plan 
may  be  brought  opposite  the  middle  of  the  panels  on  the  other 
side,  in  order  to  avoid  too  much  intersection. 

This  arrangement,  although  a  good  one,  is  by  no  means  the 
only  one,  and  in  some  cases  might  not  be  the  best.  P'or  instance, 
in  skew  bridges  it  would  be  well  to  show  the  whole  of  the  lower 
lateral  system  in  the  plan,  and  the  whole  of  the  upper  lateral 
system  above  the  elevation,  in  connection  with  the  uppermost 
view  of  the  top  chord,  which  should  be  the  plan  from  above. 
Then,  again,  if  the  bridge  be  a  large  one,  the  height  may  be  so 


OIWIXARV  IKOX  HlGHWAY-iiRllH-.ES. 


•75 


great  that  it  will  be  impossible  to  show  the  plan  below  the  eleva- 
tion ;  in  which  case  it  will  be  necessary  either  to  make  separate 
fh-.uings  for  the  plan  and  elevation,  or  to  place  one  alongside  of 
the  other  on  the  same  sheet.  In  making  tracings  of  the  work- 
ing-drawing, the  tracing-cloth  can  be  shifted  about  so  as  to 
group  similar  parts  and  so  as  to  avoid  too  much  intersection  of 
(liHerent  portions. 

i'rovided  that  any  piece  be  .symmetrical  about  a  plane  cuttino- 
It  ill  the  middle  of  its  length  and  at  right  angles  thereto,  it  uiH 
i)c  sufhcient  to  show  only  one-half  of  the  piece ;  and  the  meas- 
urement may  be  referred  to  the  end  of  the  member,  to  the 
central  plane,  or  to  both.  Where  the  same  detail  is  used  in  more 
places  than  one,  it  is  not  necessary  to  shc-A-  it  more  than  once 
provided  that  it  be  exactly  the  same  in  every  respect. 

As  an  illustration  of  how  to  make  a  working-drawincr  take 
the  case  of  the  bridge  treated  in  the  last  chapter,  and  .Assume 
tliat  the  paper  and  table  are  each  four  and  a  half  feet  wide 
Lsing  the  scale  of  an  inch  to  the  foot,  the  depth  of  the  eleva- 
tion will  be  two  feet,  and  the  width  of  the  plan  one  foot  four 
mehes      Allowing  six  inches  above  the  elevation,  and  as  much 
inore  between  elevation  and  plan,  will  bring  the  lower  side  of 
tne  plan   within  two   inches  of   the  <t^Vr^c  of    the  paper:   this 
arrangement  will  do  very  well.     The  first  step  is  to  draw  a  line 
with  the  steel  straight-edge,  as  nearly  as  possible,  without  takin- 
t'-  im.cli  trouble,  parallel  to  the  length  of  the  paper,  and  at  a 
distance  of  two  feet  si.x  inches  below  the  upper  edge      This 
line  should  be  very  fine  and  perfectly  straight.     It  can  be  made 
so  by  prolonging  it  half  the  length  of  the  straight-edge  at  a 
time,  and  afterwards  testing  it  in  several  places.     On  this  line 
take  a  ix.int  a  foot  or  more  from  the  left-hand  end  of  the  paper 
as  the  centre  of  the  end  lower  chord  pin.     Lay  off  along  this 
hiu'  with  the  greatest  possible  accuracy  the  panel  length,  until 
the  centre  of  the  bridge  be  reached:  in  this  case  twenty  feet 
must  be  laid  off  four  times.     At  the  panel  points  erect  short 
!H  rpendiculars  with  the  triangles,  and  on  the  perpendicular  at 
the  centre  lay  off  the  camber,  which  in  this  case  is  three  inches 
l-'^'c  1).  9).     Had  the  bridge  contained  an  odd  number  of  panels 
't  would  have  been   necessary  to  draw  the  middle  panel,  and 


(II 


f 


I     ■ 


176 


oRp/xA/n-  ih'ox  iin-.nwA v-nRiDCEs. 


lay  (iff  tilt'  caniluT  of  tlirce  intlics  at  each  (MkI  of  this  panel. 
Thon,  assumiiiL;  iIk-  ciirvc  of  the  chord  to  he  a  parabohi,  th  ■ 
fall  from  the  centre  to  any  panel  point  is  e(|ual  to  the  camber  at 
the  centre  niulti])lie(l  hy  the  s(|iiare  of  the  ratio  of  the  distance 
of  the  panel  point  considereil  from  the  middle  of  the  span  to 
the  half-lenji;th  of  span. 

Thus  in  the  case  considered,  the  falls  at  the  first,  second,  ainl 
third  panel  points  will  be  respectively  3(|)''^,  3(1)''^,  and  3(|)''^,  or 
\X\  i|",  and  ,''y",  makin<;-  the  hei^dits  of  these  points  above  the 
horizontal  line  respectively  3"  —  '•J^",  3"  —  i|",  and  3"  —  ■,■*,",  or 
'A"'  -i  '•  '''^''  -lu  "'  \^''i'<-'li  distances  are  to  be  laiil  out  upon  the 
perpendiculars  so  as  to  locate  the  centri's  of  the  lower  chord  pins. 
The  lenj;th  of  the  panels  as  thus  determined  differ  from  those 
of  their  horizontal  projections  by  an  inappreciable  (piantity.  If 
there  be  any  len^^thening  of  the  chord,  it  may  j^o  against  the 
play  of  the  i)ins  in  the  eyes. 

Ne.\t  join  the  consecutive  pin  centres,  producing  them  each 
way  a  little  more  than  a  jianel  length,  so  as  to  facilitate  the 
erection  of  perpendiculars  thereto.  Then  at  each  of  the  differ- 
ent centres  erect  a  perpendicular  to  each  centre  line  meetinj^ 
there,  and  bisect  the  angle  between  the  perpendiculars  :  the 
line  of  bisection  will  be  the  centre  line  of  the  post.  Great  care 
must  be  exercised  in  turning  these  right  angles  with  the  beam 
compasses,  two  points  on  each  of  the  perpendiculars  being 
found,  so  that  if  these  two  points  and  the  centre  be  iu  e.\;Kt 
line,  the  perpendicular  may  be  relied  on  as  correct.  On  eaih 
of  these  centre  lines  lay  off  the  depth  of  the  truss,  and  complete 
the  skeleton  diagram. 

A  partial  check  on  the  accuracy  of  the  construction  may  be 
had  by  measuring  the  panel  length  of  the  top  chord,  which 
should  agree  with  the  length  calculated  as  follows.      Let 

/  =  the  increase  in  tiie  ])ancl  lengUi  of  the  top  chord  above  that 

of  the  bottom  chord, 
c  =  the  cainher  at  the  centre  of  the  span, 
s  =  length  of  span, 
^/  =  depth  of  truss, 


and 


«  =  number  of  panels. 


OA'D/A'.i/^  y  f/wx  maim  -../  j  ■-nmnai.s.  ,  ^y 

Then,  according  to  the  method  ^ivc.  in  Trautwino's  «  Pocket- 

]^ook/>  =-ri.  vvhere  ./  and  .  may  he  measured  in  ^cct.  and  c 

andM.  inchc.     The  panel  length  of  the  top  chord  will  then 

Tl,r-       {'         ''     "  ''''  '^'■•"^■'  '^"^^^'^  "f  ^he  bottom  chord 
Ih.s   s  not  a  certain  proof  of  the  accuracy  of  the  vvo,V    T  vo 
consecut.vc  post  centre  hnes  might  he  ec  uaily   n    i  td    Z 
l>c.r  correct  positions,  and  on  the  same  side  though      is  u 
.c  sLnvn  ,n  the  next  panel.     A  certain  check  mus'  be  obt 

ujuai  to  each  othei.  and  agree  with  tluit  found  by  the  formula 


^=v/'^^-f(/4-^y, 


wlitTc  /;  is  the  length  rcoiihcd 

l-r  <loi,bIc-intcTsc.cti„n  hridKcs,  the  Icgth  of  the  long  clh™ 
.  s  can  be  fot,„„  by  the  nu-thod  given  in^Ap,.™,  .f "  ^ 
u„  h  of  the  .hagonal  as  „,an„fact„red  sb.m  ,1  be  one  si  tv 

latnl  length  by  about  a  thirty-second  of  an  inch 

tcNsnin  member  show  the  hcnrl^  ult).  h    •     ■•       ^.'"^  ^'^  •-^^^'' 
^^^^^^  ^n  the  length  from  c'entre  to  centre,  as  shown  on 

"iHdRier  be  more  convenient,  draw  out  the  heads  fnllM 

wi: '," ""  '"^  "'""• '  '"■•'  -■  b-  '"one  titho  c,,:, ,  • 

.  inoMded  that  both  p„,s  and  heads  diminish  to..ether 
'  "■  hammered  heads  the  method  of  eons.rne.ion  is  «ry  sim- 


Ifililt 


I' 


178 


ORDhXAKy   /A'OA  ///u Jill' A  V-nK/DGES. 


pic.  It  consists  in  describing,  as  in  Fig.  i  of  the  accompanying 
diagrams,  a  circle  of  radius  C/i,  equal  to  that  of  the  pin  hole, 
and  a  portion  of  ai.other  circle  with  a  radius  CB,  equal  to  that 

of  the  pin  hole  plus  the  product  of  one- 
half  the  depth  of  the  bar  HK  by  the 
ratio  given  in  the  table  on  p.  20 ;  then 
drawing  the  lines  DE  and  FG  parallel  tc 
the  sides  of  the  bar,  and  at  a  distance 
therefrom  equal  to  CB;  and  with  C  as  a 
centre  and  a  radius  CD,  equal  to  t>vice 
CB,  describing  an  arc  to  intersect  /;/:' 
and  FG  in  the  points  D  and  F;  finally, 
with  D  and  /^as  centres,  and  radii  equal 
to  CB,  describing  the  arcs  HL  and  KM, 
tansrent  to  the  sides  of  the  bar  at  //and 
K,  and  to  the  outer  circle  at  L  and  J/. 

For  welded  heads  the  construction  is 
as  shown  in  Mg.  2,  where  the  pin  hole 
and  bar  are  laid  out  as  before.  The  dis- 
tance AB  is  equal  to  one-half  of  UK  multiplied  by  the  ratio  given 
in  the  table  on  p.  20  ;  and  the  distance  SO  is  equal  to  UK,  or  the 
diameter  of  the  pin  hole,  whichever  be  the  greater.  The  cen- 
tres P  and  R  of  the  arcs  OBL  and  O'I'M  respectively  are  found 
by  trial ;  then  DE  and  FG  are  drawn  parallel  to  tlie  sides  of  the 
bar  at  distances  therefrom  D//  and  FK,  equal  to  one  and  seven- 
tenths  times  I'B  or  KB:  and  with  B  and  A'  as  centres,  and 
radii  equal  to  two  and  seven-tenths  times  BB  or  A'/",  or,  what 
is  the  same  thing,  e(|ual  to  D//  plus  J'B,  arcs  are  descrihed 
cutting /:>/•:  in  D,  and  FG  in  F;  finally,  with  D  and  /•"  as  cen- 
tres, and  with  radii  equal  to  DN,  arcs  are  drawn  tangent  to  the 
side,  of  the  bar  at  //  ami  A',  and  to  the  arcs  OFL  and  O'J'J/dt 
L  and  J/  respectively. 

These  constructions,  with  slight  modifications,  are  taken  from 
Trautwine's  "  Packet-Book." 

Next  show  the  iiosts  and  the  attached  sway  bracing  in  two 
projections  with  all  tiieir  details.  There  should  be  allowed  a 
clearance  of  about  an  eighth  of  an  inch  for  the  ends  of  the  posts 
inside  of  the  chord.     The  positions  for  the  stay  plates  should 


s,  are  taken  from 


OKDIXAR  ]  •  IROX  J I  hi  nil  -A  J  -HRHH;  Es.  ,  -jc, 

be  as  close  to  the  pin  as  possible,  allowing  a  little  elcarance  for 
the  diagonals      The  proper  positions  can  be  ascertained  from 
the  general  elevation.     The  lattice  bars  should  be  close  to  the 
stay  plates :  it  will  not  be  necessary  to  show  more  than  a  few 
of  them  on  each  strut,  the  positions  of  the  others   beino-  indi- 
cated hy  their  centre  lines,  as  shown  on  Plate  VI      This  plate 
contams  a  portion  of  a  vorking-drawing  for   a  model   of   t^he 
bridge  treated  in   the   previous   chapter.     The  small   scale   of 
thrce-c|uarte.-s  of  an  inch  to  the  foot  was  chosen  so  as  not   to 
make  the  model  too  large  ;  and  the  whole  working-drawino-  is 
not  gnen,  because  of  the  necessarily  limited  size  of  the  pla^e  * 
I  ho  principal   portions  are  represented  ;  so  that   one  can,  by 
studying  the  plate  closely,  learn  all  that  it  is  necessary  to  know 
ni  order  to  make  working-drawings  ;  and  students  are  recom- 
mended to  give  this  matter  special  attention. 

Xext  show  in  two  projections  the  top  chord  and  batter  brace 
u-.th  all  their  details,  and  give  several  views  of  each  connect- 
.ng-p  ate  and  other  detail  in  the  neighborhood  of  its  position  on 
t  e  e  evat.on.     The  joints  in  the  channels  and  plate  of  the  top 
chord  should  be  located  three  or  four  inches  to  that  side  of 
each  panel  point  which  is  farthest  from  the  centre  of  the  brid-^e 
-  tlKit  t  e  pin  holes  shall  be  bored  through  a  single  piece,  ami 
thrnugh  the  thicker  of  the  two  abutting  pieces      At   the  hip 
I'Hnt  It  IS  of  course  unavoidable  .o  bore  the  pin  hole  through 
the   abutting    end.s   of   the   chord    and    batter-brace    channel;. 
.\cx    pass  to  the  plan,  where  the  first  thing  to  do  is  to   draw 
parallel  to  the  original  horizontal  line  of  the  elevation  traces  of 
t.u.  central  vertical  planes  of  the   trusses  and   of  the  central 
piano  n    the  bridge,  locating  the  panel  points  verv  carefully,  and 
as  nearly  as  possible  vertically,  below  their  corresponding posi- 
■;'"^""  tl^e  elevation.       Then   arrange    the  chord  packTni  on 
<'nc  sKle  of  the  plan  so  as  to  make  the  bending-moments  on  the 
Pms  as  small  as  possible  without  luu-ing  anv  of  the  chord  bars 
i"i  I  at  too  great  an  angle  with  the  plane  of  the  truss 

a  any  of  the  panels  have  trussed  bars,  the   trussing   should 
he  here  shown,  and  the  spacing  of  the  rivet  holes  for  same  in 


Tliu  scale  lia^  been  fuitlicr  raluc.vl  by  the  oiii'Taver 


fit^SI'l 


liiiii 


1 80 


ORDIXARY  IROX  HIGinVAY-BRIDGES, 


the  chord  bars  should  be  represented  close  to  the  plan  of  the 
trussed  bars.  Near  the  packing  should  be  drawn  separate 
views  of  the  lower  chord  pins ;  giving  their  number,  cHanieter, 
lengths  between  shoulders,  diameters  and  lengths  of  reduced 
ends,  and  the  total  lengths,  also  the  sizes  of  the  nuts. 

At  the  right-hand  end  of  the  plan,  show  the  lower  latercl 
struts,  and  complete  drawings  for  the  floor  system,  including 
beams,  beam  hangers,  beam-hanger  plates,  bolts,  joists,  etc. 
Generally  the  floor  beams  will  be  all  alike :  so  it  will  be  suffi- 
cient to  represent  half  a  beam.  It  may  even  do  to  show  only 
half  of  a  lateral  strut,  although  there  are  always  several  differ- 
ent lengths  of  them  in  a  bridge,  provided  that  there  be  written 
sufficient  directions  to  enable  the  carpenters  to  frame  all  the 
struts  without  possibility  of  error.  In  writing  dimensions,  etc., 
upon  a  working-drawing,  it  is  immaterial  from  which  direction 
the  writing  be  read  ;  that  is,  it  may  be  read  sidewise,  upside 
down,  or  in  any  direction  most  convenient  to  the  draughtsman. 
In  making  tracings,  this  matter  can  be  rectified  if  it  be  thought 
advisable.  Full  directions  for  the  manufacturer  should  be  writ- 
ten on  the  drawing.  On  the  rest  of  the  plan,  show  the  uj^pcr 
lateral  struts  with  their  details  ;  all  the  lateral  rods  with  their 
turn  buckles  or  sleeve  nuts,  and  their  eyes  in  two  views  ;  the  end 
lower  lateral  strut  with  its  details,  and  its  connection  to  the 
pedestal ;  the  whole  of  the  portal  bracing  with  its  connections ; 
the  ornamental  work  ;  and  the  name  plates. 

Finally,  take  the  list  of  members,  and  go  carefully  over  the 
drawing  with  it  ;  seeing  not  only  that  each  piece  is  represented, 
but  that  there  are  sufficient  measurements  given  to  have  it 
manufactured. 

The  following  additional  directions  and  hints  may  be  found 
useful.  Refer  each  group  (if  rivets  to  some  local  Hue,  which  is 
itself  referred  to  the  end  of  the  piece,  or  some  other  promiiunt 
part.  .Show  a  section  of  each  member,  and  write  the  dinien- 
sions  of  all  channels,  angles,  Lbeams,  etc.,  near  the  secti.ui. 
Write  along  each  piece  its  extreme  length  or  lengths,  its  len-th 
from  centre  to  centre  of  eyes,  and  of  what  it  is  composed.  The 
ends  of  the  two  pieces  of  an  adjustable  rod  should  l)e  separated 
by  at  least  three  or  four  inches  in  the  turn  buckle  or  sleeve  nut. 


ORDLXARV  IRON  HIGHWAY-BRIDGES. 


I8l 


Mark  what  rivets  are  countersunk,  and  at  which  end.  If  the 
scale  of  the  drawing  be  large  enough,  the  countersinking  can 
Ik  thus  represented:  draw  full  parallel  lines  across  the  rivet 
for  countersinking  on  the  upper  side,  dotted  parallel  lines  for 
Ciumtersinking  on  the  lower  side,  and  two  sets  of  parallel  lines 
crossing  each  other  at  right  angles  for  countersinking  on  both 
sides.  Be  careful  to  always  note  how  many  rights  and  how 
many  lefts  of  each  piece  will  be  recjuired,  when  there  arc  both 
riL;hts  and  lefts. 

Do  not  forget  to  write  conspicuously  the  scale  or  scales  of 
the  drawing.  Lay  out  all  bevelled  edges  on  an  enlarged  scale, 
say  from  half  to  full  size,  and  mark  their  dimensions  along  the 
edges,  referring  all  measurements  to  a  transverse  line  through 
some  well-defined  point,  as  the  centre  of  the  pin  hole.  The'se 
measurements  should  be  checked  by  calculation.  The  slight 
bevels  at  the  joints  of  the  top  chord  should  be  treated  with^as 
much  accuracy  as  the  bevels  at  the  hip  joints  ;  but,  as  the  bevel 
is  very  slight,  it  will  be  legitimate  to  put  it  all  on  one  of  the 
abutting  ends,  making  the  other  a  square  cut. 

The  centre  lines  for  lacing-bars  on  the  under  side  of  a  strut 
should  be  dotted.  In  laying  out  a  long  row  of  rivets  — for  in- 
stance, lattice  rivets,  or  those  for  the  top  plate  of  a  chord  or 
batter  brace  — calculate  the  distance  of  some  of  the  intermediate 
rivet  holes  from  one  end  of  the  strut.  Lay  out  these  holes,  then 
interpolate  the  others  ;  because,  if  the  spacing  be  laid  out  con- 
tinuously from  one  end  with  dividers,  any  error  in  the  span  of 
the  dividers  will  be  multiplied  by  the  number  of  times  the  dis- 
tance is  laid  off. 

After  laying  out  a  complete  system  of  rivets  for  any  member, 
check  by  seeing  that  the  sum  of  the  distances  between  rivet 
holes  plus  the  distance  of  each  end  rivet  from  the  end  of  the 
nuinher  is  equal  to  the  total  length  of  the  member.  ]\Iake 
duplicates  of  as  many  ])arls  of  the  bridge  as  possible,  even  at 
the  expense  of  a  small  amount  of  iron,  not  only  to  save  time  in 
draughting,  but  also  in  the  shop,  and  to  facilitate  the  work 
in  erection. 

Arrange  to  have  as  few  loose  pieces  for  shipment  as  possible, 
and  mark  on  the  drawing  of  each  connecting-piece  to  what  it  is 


1 82 


ORDINARY  IROX  IIICIIW AY-BRIDGES. 


to  be  attached,  or  if  it  'va  to  be  left  loose.  Thus  the  hip  con- 
necting-plates should  be  attachetl  to  either  the  chords  or  batter 
braces,  sometimes  to  both  ;  those  of  the  top  chord,  to  that  por- 
tion through  which  the  pin  hole  is  bored  ;  those  for  the  upper 
lateral  struts  should  be  left  loose.  If  there  be  any  reason  to 
fear  rough  handling  of  the  iron  in  transit,  it  may  be  necessary 
to  send  some  of  the  connecting-plates  separately  ;  but  the  more 
loose  pieces,  the  more  field  riveting,  and  the  more  field  riveting, 
the  greater  the  erecting  expenses,  and  the  longer  the  time  and 
the  greater  the  risk  in  raising  the  bridge. 

Rivet  spacing  should  be  as  regular  as  circumstances  will  per- 
mit ;  and  all  changes  in  spacing  should  be  made  suddenly,  instead 
of  gradually,  so  as  to  facilitate  the  punching  of  the  holes  by 
machine. 

All  measurements  should  be  in  feet,  inches,  and  the  following 
vulgar  fractions  of  inches ;  viz.,  halves,  quarters,  eighths,  six- 
teenths, thirty-seconds,  and  sixty-fourths.  Workmen  do  not 
seem  to  understand  decimals :  so  it  is  better  not  to  use  them. 

Avoid  also  the  use  of  the  development  method,  as  it  is  beyond 
the  comprehension  of  ordinary  workmen. 

The  length  of  all  main  members  should  be  measured  on  the 
drawing,  then  checked  by  calculation. 

When  nuts  are  placed  in  a  confined  position,  —  for  instance, 
pin  nuts  in  jaws,  —  care  should  be  taken  that  there  be  ample 
room  for  them  to  turn  in  ;  as  it  is  very  awkward,  and  sometimes 
impossible,  to  screw  up  a  nut  which  is  stationary,  by  turning 
the  pin.  Nuts  in  confined  positions  may  be  turned  by  hammer- 
ing them  eccentrically. 

Be  careful  to  design  no  connection  in  such  a  manner  that 
there  will  be  rivets  that  cannot  be  driven  without  incon- 
venience.    This  remark  is  especially  applicable  to  field  riveting. 

It  must  be  borne  in  mind,  that,  no  matter  how  carefully  the 
bill  of  iron  was  prepared,  there  will  be  many  minor  changes 
found  necessary  in  making  the  working-drawings  ;  but,  as  a 
rule,  such  changes  cannot  materially  affect  the  total  weight  of 
iron  in  the  bridge. 


ORDINARY  IRON  HIGHWAY-BRIDGES. 


I  .S3 


CHAPTER   XIX. 


ORDER   BILLS   AND   SHIPl•L^fG  BILLS. 


asured  on  the 


When  there  is  neces.sity  for  haste  in  building  a  bridge,  as 
there  generally  is  in  America,  time  can  be  saved  by  sending  a 
partial  order  bill  to  the  manufacturers  before  starting  to  make 
the  working-drawings,  or  after  they  drc  partially  pencilled. 

Such  preliminary  order  bills  should  include  only  those  por- 
tions which  are  termed  in  this  treatise  "Main  Members,"  and 
those  details  of  the  sizes  of  which  the  designer  is  certain  ;  for 
instance,  stay  plates,  pins,  brackets,  and  the  plates  and  angles 
for  built  beams. 

The  length  of  the  main  members  in  the  bill  should  be  three- 
quarters  of  an  inch  greater  than  will  actually  be  required,  in 
order  to  allow  for  the  dressing  of  rough  ends  ;  and,  should  there 
be  any  doubt  in  the  designer's  mind  concerning  the  e.x-act  length 
of  any  piece,  he  should  make  the  ordered  length  great  enough 
to  cover  any  variation  which  there  may  be  in  the  design. 

Of  course,  where  there  are  bevelled  ends  on  a  piece,  the 
extreme  length  plus  the  allowance  for  waste  must  be  given. 

Where  a  number  of  small  pieces  are  to  be  cut  from  one  large 
piece,  an  extra  allowance  of  length  must  be  made  to  provide 
for  the  waste  in  cutting,  say  from  an  ei-hth  to  a  quarter  of  ;in 
nich  for  each  short  length.  After  finishing  the  pencilling  for 
a  working-drawing,  the  remainder  of  tlie  preliminary  order  bill 
may  be  made  out  and  sent.  It  should  be  divided  into  the  fol- 
lowing groups,  containing  the  measurements  indicated  :  — 


nmnncls 


No. 


Depth 


Weight  per  fuMt 


length 


Kinishfil  li;m;ih 


f  I  I 

r  i    ' 


184  ORDINARY  IROX  HICIIWAY-BRIDGES. 


Ansles  No.       'I'liickncss    I     IjCS-s    \      \Vcinlit  in;r  fool  Length  1' iniahed  Icnj;! 


I-hc,ims        '    No.  Depth         I       Weight  per  foot 


Length        -       Finished  length 


Plate. 

No.         Thickness 

Widih                         Length         i        Finished  Icni^th 

Eye  bars 


No.    '   Thickness 


Depth       Depths  of  lie.ids 


Length  centre  to 
centre  of  eyes 


Extren;e  Icntilh 


Adjustable 
rods  with 
plain  eyes 


Diameter. 


Short  I'iece. 


Long  Piece. 


No. :   Rod    Upset   Ciame-  j  Length  of 
I  end    '    tcr  pf   j       loop 

I  1  eye 


I.ength,  Diame- 
cenlrc  of  ter  of 
eye  loeiid         eye 


Length  of 
loop 


Ix'ngth, 

centre  nf 

eye  to  end 


Adjustable  rods  j 
with  bent  eyes 

No. 

DiAMETKK. 

Short  Piece. 

Long  Piece. 

Rod 

Upset 
end 

Diameter 
of  eye 

length,  centre 
of  liend  to  end 

Diameter      I.eiigth,  centre 
of  eye         of  bend  to  end 

Pins 

! 

1 

1  No. 

] 

Diameter. 

Length  between  shoulders 

Extreme  length 

Body 

Reduced 
ends 

Rollers                '  No. 

I.ength  between  shoulders                           Kxtremc  length 

Any  details  which  will  not  go  into  one  of  these  groups  will 
be  made  of  material  that  the-  manufacturer  keeps  in  stock ;  for 
instance,  fillers,  washers,  nuts,  turn  buckles,  sleeve  nuts,  orna- 


h  KiiiihheJ  length 


Finished  length 


Vini.shuti  Icngtit 


ExtrcTiiL'  Ic-iiutli 


I.ONC,  PuiCE. 


Length  of        Length, 


ORDINARY  IRON  HIGHU 'A  J '-n RIDGES.  , 85 

mental   work,  na.ne  plates,  bolts,  and    iron    hand  railing       It 
won  d  not  be  a  bad  idea  for  bridge  companies  to  keep  blank 
.snn.lar  to  the  foregoing,  for  preliminary  order  bills 

1  ins  should  be  ordered  an  eighth  of  an  inch  greater  in  diame 
ten  than  requ.red  in  the  bridge,  so  that  they\.ay  be  t     n^^^^^ 
clown     and  shoe  plates  and  roller  plates,  one-sixteen  h  of  an 
inch  thicker,  to  allow  for  planin-  ^" 

^IXrr"^'  """"'•'^"'  ^""™"--'>''  "^  '^-^  ^-^'  fro- 


No.  pieces 


Thickness 


Width 


Length 


Kind  of  wood 


] 


I.ONG    I'lIXE. 


A  ter  the  working-drawing  is  finished,  there  should  be  pre- 
pa.cd  to  accompany  it  a  final  order  bill,  in  which  are  to  be 
grouped  all  similar  pieces,  and  all  their  details  wh  cl  are 
attached  to  them  in  the  shop.  The  following  groupin"  vv  11 
cover  any  case  of  an  ordinary  iron  highway-bridge  dlw" 
according  to  the  method  of  this  treatise:—  ^lesigned 


lers        Extreme  length 


TOP    CHORD    SECTIONS. 


^Iiannels. 
''"IM'lates 
Lnver  |il,iles     . 
^lay  plates 
Lattice  bars     . 

I  'iriiic.  ting-plates 


No. 
No. 
No. 
No. 
No. 

No. 


Depth 
Width 
Width 
Width 
Width 

Width 


Weight  per  foot 
Thickness      | 
Thickness      i 
Thickness 
Thickness       I 

! 

Thickness      I 


Finished  length 
Finished  length 
Finished  length 
Finished  length 
Length  centre  to  centre  of  end 
rivet  holes 
Finished  length 


BATTER    KR.'VCES. 


I'.xtreme  length 


Channels . 
'l'»P  plates 
Cover-plates  (hip) 
^lay  plates 
Lattice  bars     . 

Cnniierting-plates 
•''liuc  plates 


No. 

Depth 

Weight  per  foot 

No. 

Width 

Thickness 

No. 

Wi.lth 

Thickness 

No. 

Width 

Thickness 

No. 

Width 

Thickness 

No. 

Wi.lth 

Thickness 

No. 

Width 

Thickness 

Finished  length 
Finished  length 
Finished  length 
Finished  length 
Length  centre  tp  centre  of  end 
rivet  holes. 
Finished  length 
Finished  length 


1 86 


ORDINARY  IRON  HIGHWAY-BRIDGES. 


CHANNEL    BOTTOM    CHORDS. 


Channels 

No. 

Depth 

Weight  per  foot 

Finished  length 

Stay  plates       .... 
I,acing-bars     .... 

No. 

Width 

Thickness 

Finished  length 

No. 

Width 

Thickness 

Finished  length 

Ke-enforcing  plates 

No. 

Width 

Thickness 

Finished  length 

Connecting  chord  heads  . 

No. 

Depth 

Thickness 

Length  centre  of  eye  lo  end, 
and  extreme  length 

POSTS. 


Channels 

1  No. 

Depth 

Weight  per  foot 

Finished  length 

Stay  plates       .... 

1  No. 

Width 

Thickness 

Finished  length 

Lattice  bars     .... 

]  No. 

Width 

Thickness 

Finished  length 

1  No. 

Width 

Thickness 

Finished  length 

Re-enforcing  plates . 

1  No. 

Width 

Thickness 

Finished  length 

Channels . 
Stay  plates 
Lacing-bars 
Jaw  plates 


UPPER  LATERAL  STRUTS. 


No. 
No. 
No. 
No. 


Depth 
Width 
Width 
Width 


Weight  per  foot 
Thickness 
Thickness 
Thickness 


Finished  length 
Finished  length 
Finished  length 
Finished  length 


END    LOWER    LATERAL    STRUTS. 


Channels .         .         .         .         • 

I-beams 

Angle  irons      .... 
Stay  plates       .... 
Lacing-bars     .... 
Jaw  plates 

No. 
No. 
No. 
No. 
No. 
No. 

Depth 

Depth 

Legs 

Width 

Width 

Width 

Weight  per  foot 
Weight  per  foot 
Weight  per  foot 
Thickness 
Thickness 
Thickness 

Finished  length 
Finished  length 
Finished  length 
Finished  length 
Finished  length 
Finished  Icngdi 

PORTAL 

STRUTS. 

Channels 

No. 

Depth 

Weight  per  foot 

Finished  length 

Stay  plates       .... 

No. 

No. 

Width 
Width 

Thickness 
Thickness 

Finished  length 
Finished  length 

law  plates        .... 

No. 

Width 

Thickness 

Finished  length 

Connecting- plate     to   batter- 
hrace    

No. 

Width 

Thickness 

l.ength  of  each  leg 

Connecting-plate  for  brackets 
to  channels  .... 

No. 

W:  'ih 

Thickness 

Finished  length 

Connecting- plate     for    name 
plates  to  channels 

No. 

Width 

Thickness 

Finished  length 

^GES. 


Finished  length 

Kiiiisheil  lenylh 

Finished  length 

Finished  length 
th  centre  of  eye  Id  eml, 
and  extreme  length 


C'h;ninels, 
I'l.it  bars . 


O/iDLYAJn'  I/W.V  HIGHlVAY-niUDGES. 
■STIFFKNKI)    mr    VERTICALS. 


Si;iy  plates       .         . 
I.,irnij,'-l)ars     . 
Kctiiforcing  plates. 
'Inissing. 


187 


No. 

Depth 

No. 

Width 

No. 

Width 

No. 

Width 

No. 

Width 

No. 

Width 

Weight  |)er  foot 
'I'hickness 

Thickness 
Thickness 
Thickness 
Thickness 


Finished  length 
Length  centre  to  centre  (if  eyes, 
and  extreme  leti^th 
Finished  length 
Finished  length 
Finished  length 
Finished  length 


Finished  length 
Finished  length 
Finished  length 
Finished  length 
Finished  length 


Finished  length 
Finished  length 
Finished  length 
Finished  length 


Finished  length 

Finished  length 

Finished  length 

Finished  length 

Finished  length 

Finished  length 

Finished  length 

Finished  length 

Finished  length 

Finished  length 

Length  of  etch  leg 

Finished  length 

Finished  length 

INTER.MEDIATE    .STRUTS. 


I-hiMins  , 

t L'  liiig-plales    . 


No.        Depth 
No.        Width 


Weight  per  fnot 
Thickness 


Finished  length 
I.engihofeach  leg 


MAIN    DIAGONALS    AND    PLAIN    CHORD    BAR.S. 


Nil-      Bepth      Thickness 


Depth  of 
heads 


Thickness   1  Di.atneter  of  '    Length  centre  to       F.x.n 


of  heads 


eyes 


centre  of  eyes  length 


HIP    VERTICALS    AND    COUXTER.S. 


No. 


Sectio 


Diameter  of  en-     Lengths  of  loop 
larged  end  eyes 


Lengths  centre  of  eyes  to  ends,  or  centre 
of  eye  to  centre  of  eye 


LATERAL    AND    VIBRATION    RODS. 


No. '  Diam, '  Diameter  of    U-iigth  centre  of  eye 
enlarged  end         to  hend  or  ioop 


Ungth  centre  of  bend  or  |   Length  centre  of  bend  or 
••■ye  to  end  of  short  piece  |    eye  to  end  of  long  piece 


STRUT.S    OF    TRUS.SED    CHORD    BARS. 


No.  of 


Sectii 


Sizes  of 
heads 


Section  of       Ungth  of      Ungth  of  strn,  cen- |  Extre.ne  length 
'"■ssmg      I     trnssing      '    tre  to  centre  of  eye  of  stmt 


SIDE    nRACING. 


^''i.  .Scctit 


•Size  of  connecting-plate 


Extreme  length  of  brace 


IRON    HAND    RAILING. 


No.  of  posts     I    Si.es  of  posts  No.  of  panels    I         SiVeofp.anel 


panel  Total  length  of  railing 


1 88 


Plates 
Angles 


ORDINARY  IROX  HIGHWAY-BRIDGES. 
nUILT    FLOOR    BEAMS. 


No. 
No. 


Wi.lth 
l-etjs 


Thickness 
Weight  per  foot 


Finished  length 
Finished  lenglh 


1 


III',  ! 


lilies 
Angles 


No. 


No. 


TRUSSED    FLOOR    ItKAMS. 


I-lie.inis  . 

Angles      . 
I'hles       . 

No. 
1     No. 
1     No. 

1  tepth 

I.e«s 

Width 

Weight  per  f.ioi                       Finished  length 
Weight  per  fmit        |                 Finished  length 
Thickness                |                Finished  length 

ROLLER    AND    BED    PLATES. 


No. 

No. 


Width 
Legs 


Finished  Thickness 
Weight  per  f(X)t 


NAME    PLATES. 


OTHKK  SEPARATE  PLATES. 


Width 


Di.imcter 


Thickness 


PIXS    AND   THEIR    NIT'--. 


Size  of  nuts 


Finished  length 
Finished  length 


No. 

Dntc. 

Finished  length 


length  under  head,  or  extreme  leii;;tli 


No.  Diameter 


.Angles  . 
Channels . 
Tee-iron  . 


No. 

No. 
No. 


BOLTS    AND    THEIR    NUTS. 


Size  of  nuts  length  under  head,  or  extreme  length 


BRACKETS. 


Legs 

Depth 

I-egs 


Weight  per  font 
Weight  per  foot 
Weight  per  foot 


ORNAMENTAL    WORK. 


No.  of  pieces 


Description 


Extreme  length 
Kxtreme  length 
I'.xtrcme  length 


1 


Finished  length 
Kinislied  length 


ORDINARY  IRON  NIGI/IVA  V-BRIDGES. 
HF.AM    IIANOKKS    AM)    TIIKIR    NUTS. 


189 


N.i.     Section 


I 


Diameter  of  I  Diameter      Siie  of  nuts  anil 
upset  end        of  eye  lockiiuis 


No.  of  nuts  and 

lock-nuts 


Length  of  one  Itg 


Finished  length 
Finished  length 
Finished  length 


Finished  length 
Finished  length 


KnllclS  . 

(  rii^s-rttcls 

>i.k-ii,irs  . 


No. 


SKTS    ()[•    KOLJ.KUS. 


No. 
No. 

No. 


Diameter 
Iliametcr 

Thickness 


Length  hc-iwecn  shoulders 
Length  hclwecn  shoulders 
Width 


FILLKRS    rOK    PINS. 


FAternal  diameter 


Internal  diameter 


TURN    nUCKLF.S    A\n    SI.KKVK    NUTS, 


No. 


Tap« 


Kxtreme  length 
F.xtrenie  length 
Kxtreme  length 


Length 


: 


F'inished  length 


I'Lilcs      . 
(Ilannels, 


No. 
No. 


JAWS. 


Width 
Depth 


Thickness 
Weiglit  per  foot 


Extreme  length 
lixtrenie  length 


head,  or  extreme  len;;lli 


r  head,  or  extreme  length 


Extreme  length 
Extreme  length 
r.xtreine  length 


No. 


Diameter 


WASIIKRS. 


Diameter 


Diameter  of  bolts 


SEPARATE    RIVETS. 


length  under  he.ad] 


Kind  of  head        Position  in  bridge    j      Parts  connected 


PIN    PILOTS. 


External  diameter 


Internal  diameter 


Some  companies  send  also  a  complete  bill  of  rivets  to  be  used 
in  the  shop  ;  but  this  is  scarcely  necessary,  as  it  is  more  properly 
the  place  of  the  manufacturer  to  prepare  such  a  bill. 


190  ONn/XAKV  INOX  HIGIin'AV-liKIlH'.ES. 

The  following  form  will  be  needed  for  the  purpose  :  — 

RIVKTS. 


MemlMir 

No,        ni.inicter         (.oiiKlli  between  IkmcIs 

1 

Kiiiil  of  heads            I'arls  tonnectcil 

An  allowance  of  three  per  cent  should  be  made  for  waste  in 
shop  rivi  *s,  and  from  ten  to  twelve  per  cent  in  field  rivets. 

If  the  hip  verticals  he  Hat  bars,  they  are  to  be  transferred  to 
the  group  of  "Main  Diagonals,  etc."  The  posts,  chord  bars, 
and  diagonals  of  trussed  beams,  are  included  under  the  general 
heads  of  "  Posts,"  etc. 

The  corresponding  form  of  "  Shipping  Bill  "  is  as  follows  :  — 


*>! 


STRUTS. 


Menilier 

No.     1        Len>;th  ccnlrc  to  end,  ()r  extreme  len^jth 

M.irk 

BARS. 


Member     No.    Section     Diameter  of  eyes    Size,s  of  heads     Length  centre  to  centre  of  eyes  ;   .Mark 


Rons. 


Member 

No, 

i 

Diameter 

Diameter  of 
eyes 

Diameter  of  1  Threads    \    l^"gth  cemre  of  eye 

upset  ends  :    R.  or  L.   ,       '"  ^■"''-  '"■  ^'=""-'=  "^ 
eye  lo  centre  of  eye 

Mark 

No. 


SIDE    BRACING. 


No.       1                .Section 

K,\treme  length                                         Mark 

IRON    HAND-RAILING. 


No.  of  posts 

No.  of  panels 

Mark,  ii'aiy 

FLOOR-BEAMS. 


Extreme  length 


Mark 


I  I'jrts  conncctcil 

\(.\e  for  waste  in 
field  rivets. 
)e  transferred  to 
osts,  chord  bars, 
nder  the  genera! 

is  as  follows  :  — 


;  lo  centre  of  eyes  j   Mark  ( 


ih  centre  of  eye 
rrti,  or  centre  of 
lo  centre  of  eye 


ORDINARY  IRON  HIGHWA  Y~BRIDGES. 
ROI,I.KK    AND    men    I'l  ATES. 


191 


No. 


Toniiion  (fixed  or  free  cnfl) 


M.irk,  if  any  I 


NAME    PI.ATKS. 


c 


No. 


Dtite 


OTHER  SEPARATE  PLATES. 


Position 


M:irk 


PINS    AND    THEIR    NUT.S. 


Nil.  ■    Uiamcter 


Length  between  shoirlclers 


F.xtreme  length 


dimensions  of  end*       Mark 


nOLTS    AND    THEIR    NUTS. 


I'iameter 


ni.-,meter  of  upset  ends         ,  Length  inrdcr  head,  or  extreme  length 


: 


URACKETS. 


Position 


Kxtreme  length 


Mark 


: 


ORNAMENTAL    WORK. 


No.  of  pieces 


Description 


Mark 


BEAM    HANGERS    AND   THEIR    NUTS. 


^'').  Diameter  of  eye 


No.  of  nuts  and  lock-nuts 


Mark 


ROLLERS. 


No.  of  sets 


1 1 

,1 

< 

1! 

'.\i 

' 

i' , 

'    i 

1 1 

ii    i 

\     " 

fiji 


192 


ORDIXA R  J  •  IROX  lUClIW  '.1 1  -BRIDGES. 
FIl.I.KKS    rOR    IMXP. 


No. 


External  ilhuiictcr  I  Inlcrnal  ilianicler 


I^iiRth 


Mark 


TURN    l!L'CKI.i:S    AND    SI.KKVl-:    NUl'S. 


No. 

Taps 

JAWS. 


No. 


INisilion 


Mark 


WASIIKRS. 


No. 


1  >ianiLtcr 


niamclcr  of  bolt 


SI".r.\R.\TK    RIVr.TS. 


No.   I    Diameter    I   I.eiiRlh  umler  head         Kind  of  head     i     Position  in  liiidge    |    Parts  conneuted 


PIN    IMI.OTS. 


No.       j  l-'..\lernal  di.unelcr 


Intern, d  diameter 


.Mark 


Tlie  followinj,^  is  the  system  of  maikini;-  iron  before  shipment 
which  the  author  would  recommend.  It  should  be  thoroughly 
comprehended  by  the  manufacturer,  the  foreman  i.i  chari^e  of 
ert'ction,  and  the  time-keeper  or  clerk,  if  there  be  either  em- 
ploved  on  the  work. 

Where  the  work  is  very  extensive,  the  time-keeper  generally 
checks  the  material  as  it  arrives  on  the  ,i;round. 

l'"irst,  if  there  be  more  than  one  span,  each  piece  of  each 
span  should  be  marked  with  a  daub  of  color  peculiar  to  that 
span  :  thus  the  first  span  may  be  white,  the  second  yellow,  the 
third  bl-'c,  etc.  ;  care  being  taken  to  choose  such  colors  as  will 
be  readily  distinguished  upon  the  iron-work. 

The  colors  may  be  marked  in  the  last  column  of  each  divisimi 


'JOES. 


OJWlXAA^y  /A'OX  Uniinr AY-BRIDGES. 


I/Onslh  Mark 


Mark 


meter  of  bolt 


ridge    i    Parts  connecttd 


Mark 


l)cforc  .shipment 
lid  be  thoroui;hly 
lan  i.i  charge  of 
re  be   either  eiii- 

-kecper  generally 
1. 

ch   piece  of  each 

peculiar  to  that 

jcond  yellow,  the 

ich  colors  as  will 

n  of  each  division 


1 

t 

I '  I 


,94  ORDLWIKV  IRON  HIGHIVAV-RRIDGES. 

Chord  bars  to  be  marked  i  A,  i  B,  i  C,  2  A,  2  B,  2  C,  -tc. ; 
the  numbers  corresponding  to  those  on  the  diagram,  and  the 
letters  denoting  the  position  in  the  panel,  A  being  for  those  on 
the  exterior  side  of  the  truss,  B  for  those  next  to  the  outside,  etc.- 

Side  braces  to  be  numbered  to  correspond  to  the  panel  points 
to  which  they  belong,  and  to  be  marked  R.  or  L. 

Iron  hand  railing  rccjuires  no  marks  except  E  on  the  end 
posts  and  panels,  if  these  be  different  in  any  respect  from  the 

others. 

Floor  beams   to  be   numbered   to  correspond   to  the  panel 

]-)C)ints. 

Roller  and  bed  plates  to  be  marked  R.  or  L.,  if  there  be  any 

difference. 

Name  plates  require  no  marks. 

Separate  plates  to  be  numbered  so  as  to  correspond  to  the 
panel  points  to  which  they  belong,  and  to  be  marked  R.  or  I... 

if  necessary. 

Lower  chord  pins  to  be  marked  L.  o,  L.  i,  L.  2,  etc.  ;  the 
numbers  corresponding  to  those  of  the  panel  points. 

Upper  chord  pins  to  be  marked  U.  i,  U.  2,  U.  3,  etc.;  the 
numbers  corresponding  to  those  of  the  panel  points. 

Portal  diagonal  pins  to  be  marked  P. 

Vibration-rod  pins  to  be  marked  V. 

Pins  at  middle  of  posts  to  be  marked  I\I.  i,  M.  2,  M.  3,  etc.; 
the  numbers  corresponding  to  those  of  the  posts. 

Lower  lateral-rod  pins  not  to  be  marked,  for  they  should  be 
shipped  attached  to  the  jaws. 

Bolts  need  no  mark,  but  should  be  boxed  before  shipment. 

Brackets  to  be  marked   P.  or  L  (portal  or  intermediate),  also 

R.  or  L. 

Ornamental  work  to  be  marked  R.  or  L. 
Beam  hangers  to  be  numbered  so  as  to  correspond  to  the 
panel  points  to  which  they  belong. 

Rollers  need  no  marks.  ,  •  ,      , 

Fillers  to  be  marked  the  same  as  the  pins  to  which  they 

'^Tur^'n  buckles  and  sleeve  nuts,  being  attached  to  the    rods 
before  shipment,  require  no  marks. 


)ond   to   the  panel 
L.,  if  there  be  any 


OliD/A'ARV  //W.y  niGHlVA  J  --BRIDC.ES.  ,  95 

Jaws  to  be  numbered  to  correspond  to  the  panel  points 
Vashers  need  no  marks  :  they  should  be  boxed,  or  strung  on 
bolls,  betore  shipment. 

Rivets  need  no  marks,  but  should  be  boxed 

r.lot  nuts  need  no  marks,  as  there  are  so  few  of  them  required 

In  addmo,.  to  these  marks,  there  should  be  others  for  those 
nK;.nbcrs  wh.ch  are  to  be  riveted  together  in  the  field,  and 
ulmh  are  assembled  in  the  shop  when  the  rivet  holes  pre- 
v.ously  punched  are  reamed.  These  marks  should  be  punched 
■nto  the  n.)n  with  a  steel  point,  and  should  consist  of  one,  two 
three  or  four  dots  upon  each  of  the  pieces  so  assembl  d,  in 
Oder  that  no  piece  during  erection  will  be  put  into  the  wrmig 


correspond  to  the 


i 

fr^ 

w  %\ 

^ 

' 

i 
j     ,- 

1 

■ 

1  > 

196 


ORDhX^lRV  IRON  HIGHWAY-BRIDGES. 


In 

il  ■'    '  ■ 

; 

11   ■ 

1 
.    1 

J 

CHAPTER   XX. 

ERECTION    AND   MAINTENANCE. 

The  number  of  men  required  to  erect  an  iron  highway-brid<];e 
will  vary  from  half  a  dozen  to  sixty,  or  even  more,  according  to 
the  length  of  span,  width  of  roadway,  location,  and  the  time 
to  be  occupied  in  erection. 

For  any  one  bridge,  there  is  a  certain  number  of  men  which 
will  be  more  economical  than  any  other  number ;  and  it  is  only 
experience  which  will  enable  one  to  tell  beforehand  what  this 

number  is.  " 

If  there  are  too  few  hands,  the  work  will  lag,  and  difficulty 
will  be  experienced  in  handling  heavy  pieces :  on  the  other 
hand,  if  there  are  too  many  men,  the  travelling  expenses,  and 
the  time  spent  in  travelling  by  the  extra  men,  will  be  wasted, 
and  the  total  amount  of  effective  work  tlone  by  each  man  per 

day  will  be  less. 

If,  for  any  reason,  there  be  need  for  haste,  it  will  be  economical 
to  have  a  large  force  of  men,  notwithstanding  the  last-mentioned 
consideration.  For  raising  ordinary  county  bridges,  the  author 
would  recommend  the  following  numbers  of  men  in  a  gang  :  io\- 
pony  truss-bridges,  six  men  ;  for  through-spans  not  exceeding 
eighty  feet,  seven  men  ;  from  eighty  to  one  hundred  feet,  ei-ht 
men  ;  from  one  hundred  to  one  hundred  and  twenty-five  feet, 
nine  or  ten  men  ;  from  one  hundred  and  twenty-five  to  one 
hundred  and  fifty  feet,  eleven  or  twelve  men  ;  from  one  hundred 
and  fifty  to  one  hundred  and  seventy-five  feet,  thirteen  or  four- 
teen men  ;  from  one  hundred  and  seventy-five  to  two  hundred 
feet,  fifteen  or  sixteen  men;  from  two  hundred  to  two  hun- 
dred and  fifty  feet,  from  sixteen  to  twenty-four  men  ;  and,  from 
two  hundred  and  fifty  to  three  hundred  feet,  from  twenty-four 


ORDINARY  IRON  HIGHWAY-BRIDGES.  197 

to  thirty-six  men.  The  long  spans  require  a  proportionately 
greater  number  of  men,  on  account  of  the  heavy  sections  For 
the  same  reason,  the  numbers  given  should  be  increased,  if  the 
bridge  be  wider  than  the  ordinary  size.  For  city  bridges,  which 
arc  proportioned  for  heavy  loads  and  for  smaller  intensities  of 
working-stresses,  the  numbers  should  be  increased  from  ten  to 
twenty  per  cent.  When  great  haste  is  necessary,  the  numbers 
.should  ])e  doubled. 

The  most  economical  number  of  men  will  depend,  too,  upon 
their  skill ;  for  green  hands  work  at  a  great  disadvantage  in 
brulge-raising.  They  do  not  know  how  to  use  their  stren-th 
and  require  the  foreman  to  stand  over  them  to  show  them  how 
to  <!..  their  work  ;  besides,  they  are  often  so  light-headed  as  to 
be  unable  to  work  aloft.  Sailors  make  excellent  bridge-men 
on  account  of  both  their  agility  and  their  training,  which  has 
taii-ht  them  to  do  in  a  few  minutes  many  a  difificult  little  piece 
of  work  that  ordinary  hands  would  puzzle  over  for  hours 

It  IS  necessary  to  have  a  few  experienced  men  in  every  o-an-  • 
the  more  of  them,  the  better,  provided  that  their  travelliito^ 
expenses,  and  wages  when  travelling,  do  not  render  their 
employment  too  expensive. 

The  cost  of  raising  a  bridge  depends  more  upon  the  foreman 
than  upon  the  men.  The  best  men  will  fail  to  do  their  full 
quota  of  work  if  the  foreman  be  not  energetic.  Nor  does  it 
suKice  to  have  simply  a  good  worker  for  a  foreman  :  he  must 
know  iiow  to  keep  the  gang  busy,  or  they  will  stand  by  and 
look  on,  while  he  does  all  the  work.  He  should  also  have  their 
K<HH  u-,11,  or  the  progress  of  the  work  will  be  unsatisfactory 

I  he  outfit  for  a  gang  to  raise  ordinary  county  bridges  should 
be  as  follows  :  — 

■  forge,  2  pairs  of  tongs,  2  button  setts  for  each  size  of  rivets 

5  ^In't-l'ins  of  each   necessary  size,   2   handle  cold   chisels,   i 
aiullc  drift  p.n,  12  cape  chisels,  6  plain  chisels,  3  wrenches  for 

\  nut.s,  3  wrenches  for  |"  nuts,  2  riveting-hammers,  i  lio-ht 
^loc  Rc,  r  heavy  sledge,  4  hand  lines  |"  diameter,  4  guy  lines 
>    diameter  by  130' long,  2  fall  lines   l"  diameter  by  no'lon-^ 

6  to  lorope  sling.s,  2  sets  8"  blocks.  2  snatch  blocks,  5   steel 


I 


198 


ORDINARY  IRON  HIGHWAY-BRIDGES. 


crowbars,  3  cross-cut  saws,  2  augers  i"  diameter,  2  augers 
I"  diameter,  4  augers  f"  diameter,  3  axes,  2  adzes,  8  timber 
trucks,  4  monkey  wrenches,  4  chains,  2  crabs,  2  holding-on  bars, 
3  jack  screws,  several  large  wrenches  for  pins,  and,  if  neces- 
sary, a  pile-driver  with  its  appurtenances.  The  ordinary  weight 
of  a  pile-driver  hammer  varies  from  sixteen  hundred  to  two 
thousand  pounds  ;  and  the  height  of  the  driver  is  about  thirty 
feet.  The  cost  for  such  an  apparatus  complete  is  about  two 
hundred  or  two  hundred  and  twenty-five  dollars. 

If  the  gang  be  a  large  one,  or  if  the  span  exceed  one  hundred 
and  fifty  feet  in  length,  the  numbers  of  some  of  the  tools  on  the 
list  will  h.;ve  to  be  increased  ;  for  instance,  those  of  the  bars, 
ropes,  and  timber  trucks. 

Bridge  carpenters  generally  carry  tools  of  their  own  :  so,  if 
there  be  much  timber  work  in  connection  with  the  bridge,  it 
will  be  sufficient  to  employ  more  carpenters,  and  not  to  pur- 
chase a  larger  outfit  of  carpenters'  tools. 

In  getting  ready  to  'erect  a  bridge,  the  first  step  is  to  prepare 
the  ground  in  the  neighborhood  of  the  site,  so  that  there  will 
be  room  to  store  the  material  and  for  the  men  to  work.  When 
the  iron  is  received  at  the  site,  it  should  be  checked,  and  niiy 
pieces  from  which  the  marks  have  been  obliterated  should  he 
re-marked.  The  iron  should  be  piled  systematically,  similar 
parts  being  grouped  ;  and  no  iron  should  be  allowed  to  lie  uix  n 
the  ground.  It  should  be  piled  so  that  there  will  be  no  trouhic 
in  getting  at  any  piece  which  may  be  required  ;  and  the  parts 
to  be  used  first  should  be  placed  nearest  the  bridge  site. 

The  piers  and  abutments  will  be  supposed  to  be  erected,  as 
this  work  does  not  aim  to  treat  of  foundations. 

The  next  step  is  to  put  the  falsework  in  place.  If  the  bed  of 
the  stream  be  dry,  or  nearly  so,  the  bottom  hard,  the  distance 
from  the  bed  to  the  lower  chord  less  than  eighteen  feet  ;  and  if 
there  be  no  danger  of  a  sudden  rise  of  water  with  a  swift  cur- 
rent, the  floor  and  joists  can  be  used  for  falsework. 

If  the  distance  from  the  bed  of  the  stream  to  the  bottom 
chord  be  greater  than  eighteen  feet,  and  the  other  conditions 
be  the  same,  timber  bents  on  mud-sills  will  be  required.  The 
size  of  a  mud-sill  should  vary  from  6"  by  6"  to  1 2"  by  1 2",  accord 


to  be   erectc(l,  as 


ORDINAR  V  IROX  HIGH II VI  V-BRHJGES.  1 99 

in-  to  the  hardness  of  the  ffround,  the  weight  upon  the  sill,  and 
the  height  of  the  falsework.  It  is  not  necessary  that  the  tim- 
bers be  square.  For  ground  not  especially  hard,  wide  timbers 
lai.l  on  their  flats  are  preferable,  because  they  distribute  the 
])ri'ssure  better. 

If  there  be  but  one  tier  per  bent,  two  posts  will  be  enough, 
when  the  width  of  roadway  does  not  exceed  si.xteen  feet.     Tiicsc- 
posts  should  batter  about  one  inch  to  the  foot,  and  should   be 
cn\ereil  by  a  cap  about  6"  by  6"  or  8"  by  8",  long  enough  to  i^-o- 
jcet  two  feet  beyond  each  truss.     The  upper  ends  of  the  po^ts 
should  lie  directly  under  the  trus'ses,  and  the  caps  should   be 
(hift-bolted  thereto,     i;  the  roadway  exceed  sixteen  feet,  there 
should  be  an  intermediate  vertical  post.     The  bent  should   be 
braced  by  diagonal  flat  timbers,  say  from  2"  by  6"  to  3"  b)-  8", 
according  to  their  length,  running  in  opposite  directions,  one  on 
each  side  of  the  bent,  and  bolted  or  spiked  to  the  posts  and  cap. 
If  there   be  two  tiers  in  a   bent,  the  inclined   posts   should 
batter  two  inches  to  the  foot  (or  three  inches  if  there  be  dan-er 
"I  High  wind),  and  there  should  be  a  vertical  post  under  eJch 
miss.     liach  tier  should   be  bracerl  with  diagonal  timbers,  as 
before.     The  greater  the  danger  of  high  wind,  the  more  effec- 
tively should  each  bent  be  braced.     Alternate  consecutive  bents 
should  also  be  braced  diagonally  on  their  outer  faces,  and  all 
consecutive  bents  should  be  connected  by  longitudinal  horizon- 
tal  planks  well  spiked  to  the  caps.     These  planks  will  be  useful, 
in  fact  often  necessary,  for  the  workmen  in  passing  from   bent 
to  bent.     If  there  be  more  than  two  tiers  per  bent,  the  batter 
"1  the  inclined  po.sts  should  be  three  inches  to  the  foot.     A 
,^o;k1  jieight  for  each  tier  is  sixteen  feet. 

Where  the  bottom  is  soft,  or  where  the  water  is  deep  and 
I'lpid,  piles  will  be  required  to  rest  the  bents  upon.  There 
should  be  from  two  to  five  piles  per  bent,  according  to  the 
width  of  the  latter;  a  pile  being  placed  below  each  vertical  and 
inclined  post.  These  piles  should  be  braced  in  the  direction  of 
the  stream  by  flat  timbers  bolted  thereto.  Any  bracing  that 
mav  he  given  them  transversely  to  the  stream  shoukf^be  at 
such  a  distance  above  high-water  level  as  to  cause  no  obstruc- 
tion to  boats,  trees,  ice,  or  other  floating  objects. 


Ji 


200 


Oh'D/A'ARV  /RO\  llhillWAV-niilDGES, 


If  the  bottom  be  bare  rock,  incaiKible  of  holdini;  piles,  the 
nnid-sills  must  again  be  resortcil  to.  Tliey  should  be  weighted 
so  that  they  may  be  sunk  into  place,  then  drift-bolted  to  tiie  roi  k. 
This  can  be  done  without  the  aid  of  a  diver.  Of  course  the  sills 
must  be  firnily  attached  to  the  lower  tier  before  being  put  do 


Wl). 


I'he  lops  of  all  piles  should  be  cut  oif  to  an  exact  level,  sn 
that,  when  the  bents  arc-  erected,  the  ui)per  surfaces  of  llu' 
upper  caps  will  lie  in  the  same  hori/ontal  plane. 

On  these  caps  should  be  placed  timber-beams  stretching  from 
one  bent  to  the  ne.xt,  and  lying  immediately  under  the  trussis: 
joists  will  answer  the  purpose.  It  is  generally  customary  to 
place  the  bents  under  the  ])anel  points  ;  but  the  author  |)refers 
to  jiut  them  two  feet  to  one  side,  so  that  the  floor  beams  may  ho 
swung  into  place  without  taking  down  the  falsework.  This 
method  may,  and  probably  will,  recpiire  an  extra  bent  at  one  end 
of  the  span;  so,  if  the  bents  be  expensive,  it  is  better  to  put  one 
under  each  panel  point,  and  remove  the  ui)i)er  tiers  before  swimm- 
ing the  floor-beams.  The  level  of  the  top  of  the  longitudinal 
beams  should  be  at  least  six  indies  below  the  feet  of  the  posts, 
so  as  to  permit  of  the  use  of  camber  blocks,  like  those  shown 
on  Plate  VII.  The  angle  which  the  contiguous  faces  make  with 
the  horizontal  (less,  of  course,  than  the  angle  of  friction  ol  the 
wood)  enables  the  untler  block  to  be  easily  knocked  out  when 
the  span   is  to  be  swung. 

The  timbers  for  the  caps  and  posts  of  the  falsework  are  gen- 
erally square,  and  the  sizes  for  the  latter  are  to  be  ft)und  from 
Table  XXXIX.,  after  the  stresses  in  them  have  been   ascer- 


tained as 


foil 


ows 


Let 


\]\  =  weight  i)er  foot  of  the  iron-work  of  the  l)ridge, 

W.,  =  average  wci,L;lu  per  foot  in  lieiglit  of  one  bent  of  falsework 

and  the  tiniliers  whose  weij;lit  it  s\ii)i)orts, 
p  =:  wind  pressure  i)er  sijuare  loot, 
A  =  area  per  lineal  fool  which  the  two  trusses  ])resenl  to  tlio  wind 

(it  is  generally  a!)0ut  five  or  six  scjuare  feel), 
A!  —  the  average  area  subject  to  wind  pressure  per  foot  in  height 

on  one  bent,  ami  its  share  of  longitudinal  bracing, 
/=  i)anel  length, 


OA'D/NAJiV  IRON  niGHWAY-lUUiHil'US. 


IS  strctcliin<r  fro 


201 


:mtl 
then 


.•„  c.,,  c„  etc.  =  horizontal  distance  l)otu-ecn  centre  h'nes  of  inch-ned 
posts  niuasured  along  the  caps, 
rt'=  dejUh  of  truss, 
./,. ./,,  d„  etc.  =  heights  of  the  different  tiers  commencing  at  the  top 

A  =  vertical  distance  between  centre  of  chonl  and  upper 
cap  of  bent, 


6  =  the  angle  wliieh  the  inclined  posts  make  with  the  ver- 
tical ; 

pA/=  i)rossnre  on  trusses  at  each  panel  point, 
/>/t'l/^  =  i)ressiire  on  U])per  tier, 
/>A',/,  ==  |)ressure  on  second  tier  from  top, 
/.'/V3  =  pressure  on  third  tier  from  top, 

aii.l  the  stresses  /'„  F,^,  /r,  etc.,  in  the  inclined  posts  of  the 
hrst,  second,  and  third  tiers  respectively,  will  be  Lnven  bv 
the  equations,  ^ 


L-.-'-  +  . 


sec  6, 


/;  =  c»v:c.  +  &c. 


hcse  formulas  are  obtained  under  the  supposition  that  the 
■nclincd  posts  are  not  aided  by  the  vertical  ones,  which  suppo- 
■sition  IS  necessary  in  order  to  avoid  anibi-uity :  it  would  be 
correct,  were  the  falsework  on  the  verge  of  overturning  If 
the  tunber  be  green,  the  error  thus  made  upon  the  side  of 
safety  .spdvantageous  ;  but,  if  the  timber  be  dry  and  of  good 
quality,  ,t  IS  permissible  to  make  a  slight  reduction  in  the  size 
K.vcn  by  Table  XXXIX.     In  applying  the  table,  find  the  size  of 


202 


oRD/A'AJiy  /A'OA'  n/ami'Ay-jiR/ih,/:s. 


'.      its 


scjiiarc  timber  rec|iiirc(l  for  a  stress  I\  and  lenj^th  ^/,  sec  0,  that 
for  a  stress  l'\  ami  length  d^  sec  ^,  etc.,  then  take  the  greatest  of 
these  sizes. 

The  vertical  posts  should  be  .strong  enough  to  withstand  a 
working-stress  given  by  the  equation, 

where  //  is  the  number  of  the  tier  considered,  and  S  the  stress 
in  the  corresponding  vertical  post. 

One  dimension  of  the  vertical  posts  should  be  the  same  as 
the  side  of  the  square  which  is  the  .section  of  the  inclined  posts; 
so  that  the  diagonal  braces  may  be  flush  with  the  entire  faces 
of  the  bents,  and  be  bolted  to  the  verticals  without  the  inter- 
vention of  filling-pieces. 

These  equations  seem  very  long,  and  no  doubt  many  practical 
bridge  foremen  would  look  upon  them  with  disdain  :  neverthe- 
less, if  the  falsework  is  to  be  designed  by  any  other  method 
than  that  of  guessing,  this  is  the  way  in  which  it  should  he 
done.  The  more  elevated  the  bridge,  the  more  important  does 
it  be  ome  to  properly  proi)ortion  the  falsework.  The  values  of 
]Vi  and  A'  will  have  to  be  assumed,  or  roughly  calculated,  before 
applying  the  equations.  The  other  quantities  are,  or  shoiikl 
be,  known.  The  value  of  />  may  be  taken  from  ten  to  fifteen 
pounds  per  square  foot,  unless  the  situation  be  mure  than  ordi- 
narily exposed,  when  it  may  be  taken  at  twenty  pounds. 
Bridge  companies  can  afford  to  risk  the  chance  of  a  hurricane 
striking  the  bridge  before  it  is  swung. 

The  sections  of  the  caps  are  generally  made  the  same  as 
those  of  the  inclined  posts.  The  caps  should  be  dapped  to 
receive  both  upper  and  lower  ends  of  vertical  and  inclined 
posts.  The  vertical  posts  should  be  drift-bolted  through  the 
caps,  the  bolt  being  long  enough  to  project  five  or  si.x  inches 
into  each  post ;  and  the  inclined  posts  should  be  held  in  place 
by  wooden  splice  pieces,  one  on  each  side  of  the  bent,  project- 
ing above  and  below  the  cap,  and  fastened  at  each  end  by  a 
bolt  passing  through  the  two  splice  pieces  and  the  post.  This 
attachment  may  be  used  for  the  vertical  posts  instead  of  the 


OKJ)/\.tA'y  /KOX  HIGIlWAY-Iil^lDaES. 


203 


h  to  withstand  a 


and   .S'  the  stress 


drift  bolts,  if  it  bo  preferred.     For  additional  security  against 
slippin-,  a  third  bolt  may  be  put  throu-h  the  splice  pieces  and 
the  cap;  or  cleats  may  be  nailed  to  the  latter  above  and  below 
at  the  toe  of  each  inclineil  post. 

All  bolt  holes  in  timber  should  be  accurately  located  and 
bored  before  the  falsework  is  erected.  On  this  account  the 
bents  should  be  all  built  after  one  pattern,  so  that  the  parts 
may  be  interchangeable.  If  the  bents  be  of  different  hei-hts 
the  variation  may  be  effected  in  the  lowest  tiers.  Holt.s*  arc' 
always  preferable  to  spikes  for  connecting  timbers,  especially 
when  the  falsework  has  to  be  taken  down,  and  re-erected  for 
another  span.  Care  should  be  taken  to  avoid  any  unnecessary 
injury  to  the  timber,  in  order  that  it  may  not  be  sold  at  too 
tjreat  a  loss  after  the  work  is  finished. 

There  should  be  at  least  two  plank  walks  on  top  of  the  lower 
falsework,  exterior  to  the  trusses,  and  a  runway  midway  between, 
formed  of  several  joists  set  on  edge  for  the  purpose  of  brin-in- 
out  the  material  thereon  upon  timber  trucks.  ''    '"^ 

The  posts  of  the  upi)er  falsework  should  rest  on  the  caps  of 
the  lower  falsework,  a  few  inches  inside  of  the  trusses,  unless 
the  i)ents  are  placed  beneath  the  panel  points,  in  which  case 
they  should  be  placed  two  feet  to  one  side :  they  should  be 
attached  to  the  caps  by  splice  timbers  and  cleats.  The  hei-ht 
of  the  upper  falsework  should  be  such  that  the  upper  surfac'of 
the  caj)  wdl  be  at  least  si.x  inches  below  the  under  sides  of  the 
upiK-r  chord  .sections,  so  as  to  pennit  of  the  use  of  camber 
i)l(ieks  between. 

The  author  would  suggest  that  the  end  bents  of  upper  false- 
work be  made  three  or  four  feet  higher  than  the  others,  and  the 
use  of  four  posts  instead  of  two  (one  on  the  inside,  and  one  on 
tlie  outside,  of  each  truss),  in  order  to  aid  in  raising  and  holdino- 
ui  place  the  heavy  batter  braces.  After  the  latter  are  put  in 
position,  a  horizontal  timber  may  be  firmly  bolted  to  the  bent  at 
the  level  of  the  other  bent  caps,  for  the  temporary  floorin-  to 
'■^'st  upon.  Stout  beams  stretching  from  bent  to  bent  wil?  be 
icciu.red  as  fulcra  for  the  levers  by  which  the  chord  sections 
a>e  handled.  The  ui.per  falsework  should  be  braced  by  diao-o- 
iKil  timbers,  both  longitudinally  and  transversely.     The  sizes'of 


J 


204 


()A'/)/A.iA'i-  /A'ox  ///(,// ii'.i  r-/.7v'//n;/;.v. 


the  posts  should  tjencrally  be  about  6"  by  6" :  when  the  trusses 
are  hij;h  and  the  chord  sections  heavy,  it  might  be  well  to 
increase  the  size  to  7"  by  7".  The  caps  of  the  upper  falsework 
should  be  deeper  than  their  breadth  ;  because  they  have  to  act 
as  beams,  and  may  be  subjected  to  considerable  shock  when 
the  chord  sections  are  being  put  in  place.  The  method  of 
bracing  shown  on  Plate  VII.  is  specially  advantageous  in  this 
respect. 

In  both  upper  and  lower  falsework,  the  diagonal  bracing  in 
planes  parallel  to  the  axis  of  the  bridge  should,  for  economy's 
sake,  be  placed  between  alternate  pairs  of  bents  ;  tiiat  is,  every 
other  space  between  bents  should  be  braced.  The  end  spaces 
shoulil,  however,  be  braced  in  any  case. 

Plate  \T1.  gives  an  illustration  of  how  the  working-drawings 
for  falsework  should  be  made.  For  economy  of  space,  the 
scale  has  been  taken  at  an  eighth  of  an  inch  to  the  foot ;  but  it 
should,  if  intended  for  an  actual  case  of  framing,  be  four  times 
as  great.  A  drawing  of  this  kind  should  be  accompanied  by  bills 
of  lumber  and  iron,  prepared  in  a  similar  manner  to  that  given 
in  Chapter  XIV.  for  the  span.  Measurements  of  distances 
between  bolt  holes  should  be  both  calculated  and  scaled. 
Those  on  Plate  VII.  were  simply  scaled,  as  the  plate  is  intended 
for  illustration  only. 

The  foreman  of  the  work  should  be  provided  with  a  blue 
print  of  the  working-drawings  for  the  bridge,  unless  the  type  of 
structure  be  one  with  which  he  is  perfectly  familiar.  He  must 
also  be  provided  with  a  "  Raising  Bill,"  which  should  consist  of 
a  skeleton  diagram  of  one  truss,  with  the  following  information 
written  thereon  :  — 

Size  of  each  truss  strut,  and  tie,  and  mark  for  same,  also  number  of 
pieces  of  same  in  a  panel  of  one  truss. 

Diameters  and  lengths  S.  to  S.  of  truss  pins,  with  their  marks. 

Diameters,  lengths,  and  marks  of  fillers  for  same. 

Sizes  and  marks  of  all  separate  plates  belonging  to  the  trusses,  each 
in  its  proper  position. 


■    »' 

.if 

sr 

O/W/A'.l/n-  /A\hV  niC.HUWV-lih'llH-.ES. 


205 


to  the  trusses,  each 


A  (liafjram  for  the  lower  lateral  system,  giving  the  following 
information  :  — 

Sizes  and  marks  of  rods. 

riisitions  of  same,  showing  which  eyes  arc  to  go  next  the  trusses. 

Sections,  len},'ths,  and  marks  of  lateral  struts. 

Diameters  and  lengths  of  lateral  pins,  if  any. 

Diameters  and  lengths  of  fillers  for  same. 

Si/.es  and  marks  ol  jaws,  if  there  be  any  difference  between  them. 

A  diagram  for  the  upper  lateral  system  and  portal  bracing, 
giving  the  following  information  :  — 

Sizes  and  marks  of  rods. 

Positions  of  same,  showing  which  eyes  are  to  go  next  the  trusses. 

.Sections  and  marks  of  lateral  and  portal  struts. 

Diameters  and  icngtlis  of  jjortal  pins. 

Diameters  and  lengths  of  fillers  for  same. 

1  )iameter  and  length  under  head  of  portal  strut  attaching  bolts. 

lie  should  also  be  provided  with  a  plan  of  the  bottom  chord 
packing  (the  transverse  dimensions  being  exaggerated,  so  that 
the  .size  of  each  piece  may  be  written  thereon),  a  bill  of  bolts, 
giving  the  number  and  position  of  each  kind,  and  a  clear  state- 
ment of  the  system  of  marking  the  iron. 

liefore  starting  to  erect  the  bridge,  the  foreman  should  study 
carefully  all  the  plans,  so  that  he  will  have  a  clear  picture  of 
the  bridge  in  his  mind's  eye,  and  will  not  have  to  be  continually 
referring  to  the  drawings  during  the  erection.  On  a  work  (If 
any  magnitude,  there  should  be  kept  on  hand  a  few  standard 
nuts  of  each  size  ordinarily  used,  so  that  the  loss  of  a  nut  01 
two  will  cause  no  delay :  for  the  same  reason  there  should  be  a 
tew  extra  bolts  of  each  size. 

The  material,  as  a  general  rule,  is  all  piled  on  one  side  of  the 
>trcam  :  the  raising  should  therefore  be  commenced  at  the  other 
side,  so  that  the  passage  of  the  material  will  not  interfere  with 
the  work.  If  there  be  no  objection,  the  far  end  of  the  bridge 
should  be  the  fixed  one,  so  as  to  start  from  something  pernia- 
nent ;  but  this  is  not  absolutely  necessary. 

To  illustrate  the   method   of  raising,  take,  for  example,  the 


2o6 


ORDINARY  IRON  HIGHWAV-nRIDGES. 


iiHIl' 


M 


bridge  treated  in  Chapter  XVI.,  and  assume  that  the  founda- 
tions, with  their  anchor  liolts  and  falsework,  are  in  place.  The 
first  thing  to  be  done  is  to  lay  out  the  centre  line  of  the  bridge 
upon  the  falsework  caps,  marking  it  with  a  small-headed  tack 
on  each  cap,  then  the  centre  lines  for  the  trusses  in  the  same 
way.  This  can  be  done  either  with  a  transit,  or  with  a  carpen- 
ter's chalk-line ;  care  being  taken  to  make  the  transverse 
measurements  to  the  outer  lines  exactly  perpendicular  to  th«; 
central  line.  A  test  of  the  accuracy  of  the  perpendiculars  can 
be  made  by  the  three,  four,  and  five  method,  using  a  tape-line. 
Next,  mark  the  exact  positions  of  the  panel  points  upon  the 
longitudinal  beams  under  the  trusses,  and  place  the  camber 
blocks,  levelling  over  them  so  as  to  make  the  lines  joining  the 
central  points  of  their  upper  surfaces  parallel  to  the  curve  of 
the  chords.  It  is  better  to  have  the  blocks  a  trifle  high,  say,  an 
eighth  of  an  inch  near  the  centre,  and  a  sixteenth  of  an  inch 
near  the  ends. 

Four  small  nails  will  hold  each  pair  of  camber  blocks  from 
slipping  during  the  work,  and  they  can  be  left  so  as  to  bo 
easily  extracted  before  swinging  the  bridge.  Next  transfer  the 
centre  lines  of  the  trusses  to  the  tops  of  the  camber  blocks,  and 
mark  accurately  the  first  panel  points  from  the  fixed  end,  then, 
starting  there,  pack  the  chord  bars  of  both  chords.  It  might 
be  convenient  to  have  a  few  hard-wood  pins  to  fit  the  holes 
pretty  tightly,  so  as  to  aid  in  getting  the  bars  properly  placed 
longitudinally. 

After  the  chord  packing  has  made  some  progress,  run  out  the 
two  batter  braces,  and  hoist  them  into  place  by  means  of  pulleys 
attached  to  the  cap  of  the  first  bent  of  falsework,  which  bent 
should  have  been  previously  guyed  and  braced  so  that  it  canmit 
possibly  be  disturbed  by  the  effect  of  the  pulleys.  As  soon  a.s 
each  batter  brace  is  raised,  and  the  anchor  bolts  pass  through 
the  holes  in  the  shoe  plate,  the  nuts  should  be  tightly  screwed 
down  in  order  to  aid  in  holding  the  batter  brace  in  position. 

It  will  not  do,  however,  to  rely  solely  on  these,  for  the 
threads  of  the  end  bolts  might  be  stripped  :  consequently  a 
hard-wood  supporting  block  must  be  strongly  bolted  to  the  two 
adjoining  posts  of  the  bent  of  the  upper  falsework.     This  block 


igress,  run  out  the 


ORDINARY  IRON  HIGHWAV-niUDGES.  207 

Should  have  a  bevelled  ed-e,  the  angle  of  bevel  bein-  equal  to 
the  slope  of  the  batter  brace,  so  that  the  iron-work  will  not  rest 
on  a  sharp  edge  of  wood.  If  the  lattice  bars  interfere  with  the 
hcaruig,  as  they  arc  liable  to  do,  rough  notches  can  be  cut  in  a 
ninuite  on  the  bevelled  face  so  as  to  bring  the  bearing  upon  the 
channels. 

Meanwhile  the  end  lower  lateral  strut,  the  portal  struts,  and 
the  portal  and  end  lower  lateral  rods,  having  been  run  out,  the 
thiee  struts  are  to  be  put  into  place  ;  the  upper  ones  being  re- 
tained there  by  their  connecting  bolts,  and  the  lower  one  by  the 
end  pins,  which  should  also  pass  through  the  chord  bars,  fillers, 
and  end  lateral  rods. 

Such  small  portions  of  the  structure  as  pins,  fillers,  and  beam 
hangers,  should  not  be  brought  out  upon  the  falsework  until 
required  for  use,  for  fear  of  their  being  lost  overboard.  Nothing 
more  will  be  said  about  running  out  these  and  other  sniall  por 
tions.  but  it  will  be  assumed  that  they  will  be  at  hand  when 
wanted.  It  should  be  an  understood  thing  between  the  fore- 
man and  the  men,  that  any  one  who  drops  any  portion  of  the 
hridge  into  the  water  forfeits  a  certain  amount  of  his  wages 
.Such  an  arrangement  will  make  green  hands  a  little  more  care- 
ful than  they  are  apt  to  be  generally. 

As  the  portal  rods  are  adjusted  by  turn  buckles  with  sino-le 
tap  ends,  they  may  be  omitted  until  after  the  portal  struts  are 
riveted  to  the  batter-braces,  because  the  riveters  can  then  work 
to  better  advantage.  They  can  be  left  upon  the  abutment  until 
ret|iiired. 

•Next  run  out,  and  hoist  upon  the  falsework,  by  means  of 
pulleys  attached  thereto  and  timbers  used  as  levers,  the  end 
.sections  of  the  top  chords,  working  them  into  place  by  the 
lovers,  and  attaching  them  temporarily  at  the  hips  by  bolts, 
puttnig  in  at  the  same  time  the  end  diagonals,  but  omitting  the 
liip  verticals  and  fillers,  so  that  room  may  be  left  for  the  hold- 
m,-;-on  bars.  The  other  ends  of  the  chord  sections  rest  on  the 
(.amber  blocks. 

Next  run  out,  and  hoi.st  into  place,  the  first  vertical  posts, 

Ivttmg  the  upper  ends  lie  in  the  open  ends  of  the  chord  sec- 
tions. 


?o.s 


ORf^X.lR]-  /NO.\   lin'.inVAY-BlUDGES. 


m 


Now  start  the  rivet  i;ani;-  at  work  on  tlie  portal,  and  let  them 
follow  up  the  work  as  it  progresses,  not  leavinij  the  portal  until 
they  have  made  the  hip  attachment,  connected  the  portal  struts, 
and  put  the  brackets  and  ornamental  work  in  place. 

Next  briny;  out  the  second  sections  of  the  top  chords  and  the 
second  set  of  diagonals.  Raise  the  chord  sections  into  place, 
as  before,  with  pulleys  and  beam  levers,  holding  them  there 
until  temporary  bolts  are  put  into  a  few  holes  through  the  con- 
necting-plates, filling-plates,  and  channel  webs,  and  until  the 
pins  are  run  through  the  posts,  diagonals,  and  fillers.  The  latter, 
in  this  case,  will  not  interfere  with  the  riveting. 

Ne.xt  run  out  and  put  into  place,  as  before,  the  second  pair  of 
posts  ;  then  bring  on  the  third  sections  of  the  chords,  the  third 
set  of  main  diagonals,  and  the  first  set  of  counters,  putting  all 
three  into  place  as  before,  and  so  on  until  the  end  of  the  bridge 
is  reached.  Meanwhile  the  wooden  lower  lateral  struts  should 
have  been  framed,  and  the  jaws  attached  to  their  end's. 

Just  before  the  riveters  complete  the  riveting  of  the  jiortal, 
the  first  upper  lateral  and  intermediate  struts  should  be  run 
out,  and  bolted  into  place  ;  but  the  upper  lateral  and  vibration 
rods  should  be  omitted,  as  they  would  be  in  the  way  of  the 
riveters,  and  can  be  readily  inserted  afterwards. 

About  the  time  that  one-half  the  span  is  erected,  commence 
running  out  the  lower  lateral  struts  and  rods,  putting  them  into 
place,  inserting  the  hip  verticals  and  fillers,  and  coupling  the 
lower  chords  into  their  final  position,  leaving  the  beam  hangers 
lying  horizontally,  so  that,  when  the  longiludinal  supporting- 
timbers  are  removed,  they  will  drop  into  their  proper  places. 

A  little  before  the  riveters  reach  the  end  of  the  span,  the 
upper  lateral  and  vibration  rods  slK)uld  be  put  into  place,  and 
screwed  up  about  the  right  amount. 

When  the  end  of  the  bridge  is  reached  by  the  riveters,  and 
as  soon  as  they  have  ri\eted  the  hip  connection,  and  attache,', 
the  main  diagonals  and  hip  verticals,  the  last  couplings  of  the 
bottom  chords  can  be  made  at  the  pedestals. 

The  shoes  rest  upon  the  rollers,  which  should  have  been  put 
in  exactly  transverse  to  the  direction  of  the  bridge,  and  blocked 
so  that  they  cannot  move. 


ORDIAARV  IROX  niGini-AV-BRIDGES.  209 

The  last  connection  for  each  truss  can  easily  be  made  by 
raising  the  h.p  either  with  levers  or  by  jack-screws,  and  either 
pressing  against   the   shoe  with  jack-screws   abutting  against 

<,cks  chained  to  the  roller  plate,  or  by  attaching  a  ptir  of 
blocKS  to  the  pedestal  and  first  panel-point  lower  chord  pin 

After  the  final  coupling  has  been  made,  and  the  riveting  is 
fin.shec  knock  out  the  upper  chord  camber  blocks,  so  as  to 
bring  a  the  weight  of  the  upper  part  <,f  the  bridge  upon  the 
posts  ;  then  take  down  the  upper  falsework 

Next  knock  out  the  camber  blocks  of  the  lower  chords,  lovvcr- 
.n,^^them  together  gradually  so  as  to  bring  no  shock  upon  the 

X.xt  run  out  the  first  floor  beam  to  the  end  of  the  bridge,  and 
rcn.ne  the  runway  of  the  second  panel,  in  order  that  the  beam 
nuiy  be  dropped  between  the  lateral  struts  and  lateral  rods,  and 
swung  into  place,  lowering  it  beneath  the  ends  of  the  han-^ers 
then  raising   it  up.  inserting  the  filling-plates,  putting  on%he 
anger  plates,  and  screwing  up  the  nuts.     lu  this  way  attach 
11  t  c  loor  beams,  seeing  that  the  hanger  nuts  are  screwed  up 
rnily   but  not  to  such  an  extent  as  to  endanger  stripping  thL 
'vads.      1  hen  bolt  all  the  wooden  lateral  struts  to  the  iTeams 
Iinuigh  the  holes  previously  bored,  which  holes  should  be  at 
Ic:.st  a  quarter  of  an  inch  greater  than   the  diameter  of  the 

X.xt  screw  up  every  adjustable  rod  to  the  proper  tension, 
u  uh  can  be  ascertained  by  the  sound  they  make  when  tappec 
"illi  a  hammer.  a^^'- 

Xcxt  uash  off  any  mud  or  other  impurity  that  there  maybe 

ho  in.n-woik.  and  give  it  two  good  coats  of  paint  wherLer 

he  —sh  will  reach.     The  best  kinds  of  paint  to  use  are  lead 

-n  s,  when  they  can  be  obtained  unadulterated;  but  they  are 

""" -^o'l.  Iron  oxide  is  a  good  paint,  but  requires  more  fre- 
H^'-'t  a-newal.  The  color  should  be  such  as  to  readily  show  any 
M."  of  r..t :  various  shades  of  gray  are  efficient  in  L  respect 
•""1  'He  at  the  same  time  pleasing  to  the  eye 

IlKrc  remains  nothing  now  to  be  done  except  to  put  on  the 
i-^S  floor,  hand  railing,  and  felly  plank,  a  matter'so  simple 


210 


ORDINARY  IRON  IIIGIllVA  V-BRIDGES. 


that  it  is  unnecessary  to  describe  it  here  ;  the  only  point  worthy 
of  attention  being,  that  the  joists  should  be  dapped  one  inch 
on  to  the  lateral  struts,  and  that  they  should  go  on  so  hard  that 
it  will  be  necessary  to  drive  them  into  place.  This  can  bo 
accomplished  by  cutting  each  dap  a  sixteenth  of  an  inch  short, 
and  bevelling  the  end  of  one  dap  slightly,  in  order  to  give  the 
joists  a  start  when  they  are  being  driven  down.  When  they 
come  to  their  bearings,  they  should  be  spiked  to  the  lateral 
struts  by  a  five-inch  spike  at  each  end,  driven  obliquely. 

In  regard  to  the  flooring,  Mr.  James  Owen,  C.E.,  in  a  paper 
read  before  the  American  Society  of  Civil  Engineers,  specifies 
as  follows  :  "  Lay  no  plank  wider  than  nine  inches.  This  pre- 
vents wide  joints  in  shrinkage.  Bore  all  holes  for  the  spikes  to 
prevent  splitting,  and  put  no  spike  nearer  than  four  inches 
to  the  end  of  the  planking.'^ 

In  long  bridges  of  several  spans,  it  may  be  economical  to  dis- 
pense with  the  upper  falsework  by  using  a  travelling  derrick, 
running  upon  wooden  stringers,  for  the  purpose  of  handling  the 
heavy  ''sections.  Under  these  circumstances,  the  whole  of 
the  portal  might  be  connected  while  lying  upon  the  falsework, 
then  hoisted  into  place  in  one  piece,  and  supported  there  In- 
shore timbers  from  the  first  bent  of  falsework.  The  brid-c 
should  be  completed  as  the  traveller  retreats  :  otherwise  there 
will  be  difificulty  in  carrying  the  members  past  the  traveller. 
The  material  should  be  brought  on  cars  within  reach  of  the 

derrick.  ,     r  ,  ,        , 

The  last  thing  to  be  done  is  to  take  down  the  falsework,  ami 
draw  the  piles  f"om  the  bed  of  the  stream.  The  latter  is  easily 
accomplished  by  a  crab  on  the  bridge  ;  the  rope  being  attached 
to  the  head  of  the  pile,  which  is  vibrated  transversely  ni  all 
directions  while  being  lifted  by  the  tension  of  the  rope. 

There  is  no  reason  why  a  well-designed  iron  highway-brul-e, 
when  properly  cared  f.-r,  should  n<.t  last  forever.  Under  loads 
which  are  light  and  slowly  moving,  compared  to  those  of  rail- 
road-bridges, the  iron  cannot  possibly  wear  out ;  and,  when 
properly  protected  from  the  weather,  it  cannot  rust.  Of  course 
the  wooden  parts  of  the  structure  must  be  replaced  from  time 
to  time  as  they  wear  out  or  decay. 


ORDINAR  V  IRON  HIGH W A  V-B RIDGES.  2  \  r 

When  knots  begin  to  project  above  the  surface  of  the  floor 
they  should  be  adzed  off,  both  for  the  comfort  of  those  drivin-' 
over  the  bridge,  and  to  prevent  vibration.  After  half  an  inch 
has  been  worn  off  one  side  of  the  planks,  they  should  be  turned 
over;  and  when  another  half-inch  has  been  worn  off,  or  before 

bcTqlced  '"''"'^  '''''''  ''^"'  °^  ''''^"'''  ^^  ''"'">''  *^">'  should 
It  would  be  well  for  county  commissioners  to  buy  all  the 
liunbcr  needed  for  renewal  a  year  before  required  for  use  so 
that  It  may  be  well  seasoned. 

Iron  bridges  should  be  thoroughly  inspected  for  rust  spots  at 
least  once  a  year;  and.  if  any  be  found,  the  bridge  should  be 
rcpauuccl     One  or  two  spots  in  places  where  something  might 
have  rubbed  off  the  paint  may  be  touched  up  with  a  brush  ;  but 
generally  speakmg,  when  rust  spots  begin  to  appear,  it  show 
that  two  good  coats  of  paint  are  required  Immediately 

I  he  adjustable  members  should  be  tested  occasionally  by 
tappu^g  wth  a  hammer.  This  duty  should  not  be  intrusted  to 
an  .gnorant  workman,  who  will  turn  away  on  the  nuts  until  he 
s  ears  the  thread  or  breaks  the  rod.  .  Whenever,  in  driving  over 
a  bruise,  any  of  th.  iron-work  rattles,  it  shows  that  something  is 
ou  ;f  fj-tmcnt.  Generally  speaking,  a  well-proportioned 
H     budge  wdl  not  get  out  of  adjustment  unless  some  one 

rit"  ff  ""''  "  '"^"  '"^''^^^-  ^^'^h  combination 
bndge.  It  ,s  a  different  matter,  for  the  shrinkage  of  the  wood 
may  loosjn  the  counters. 


11! 


'm 


-  ■'  <  • 


APPENDIX    L 


A   NEGLECTED  CONSIDERATION   IN   HIGHWAY-BRIDGE 

DESIGNING. 

Sim: ciFicATioNs  for  highway-bridges  generally  call  for  strength 
to  resist  a  wind  pressure  of  at  least  thirty  pounds  per  square 
foot  of  exposed  surface  ;  but  there  are  many  such  structures  in 
the  United  States  whose  trusses  would  not,  unaid-^d,  withstand 
this  pressure.  Granting  that  the  lateral  rods  are  large  enough, 
that  the  upper  lateral  and  portal  struts  have  sufficient  strength 
to  resist  both  direct  thrust  and  bending,  and  even  that  the  lower 
lateral  rod  connection  is  all  that  could  be  desired,  still  the  bridge 
may  be  far  from  fulfilling  the  requirements,  as  the  following 
investigation  will  show  :  — 


Let 


and 


then 


/  =  the  assumed  pressure  per  square  foot, 

A  =  the  area  in  square  feet  per  lineal  foot  of  the  vertical  pro- 
jection of  that  i)art  of  the  structure  lying  below  a  hori- 
zontal i)lane,  whicli  passes  midway  between  the  chords 
of  a  through  Pratt-truss  bridge  (the  windward  truss  and 
hand-rail  are  not  supposed  to  slielter  the  leeward  ones)  ; 


///  =  IV  =  wind  load  per  lineal  foot  for  the  lower  lateral   system  when 
the  bridge  is  empty. 
Let 

^1  =  the  total  area  of  bridge  per  lineal  foot  exposed  to  the  wind 

pressure, 
//  =  the  vertical  distance  of  the  centre  of  pressure  above  the 

level  of  the  bed-plate, 
/  =  the  panel  length, 

"5 


Ik 


2l6 


i\  • 


I 


I 

■      '4 

II 

1 

■'"i 

\  >         ' 
\  : 

1 

f 

I: 

and 


APrKXDIX    I. 

b  =  clear  width  between  trusses, 
c  z=  width  of  one  truss, 
(/  =  depth  of  trusses, 
lV^  =  dead  load  per  lineal  foot  for  one  truss, 

ly^  _  reduced  dead  load  per  lineal  foot  for  the  windward  truss ; 

then  the  overturning  moment  of  the  wind  per  lineal  foot  is /J,//, 
and  it  has  the  same  effect  as  that  of  a  couple  of  lever-arm  /;  +  ,-, 
and  force, 

b-\-c' 

that  is,  the  weight  per  foot  on  the  leeward  truss  is  increased, 
and  that  on  the  windward  truss  is  decreased,  by  this  amount, 
which  gives  the  equation, 

n  =  number  of  panels  in  the  bridge, 

n   =  number  of  any  panel,  counting  from  the  nearest  end  of 
the  span ; 


Let 
and 

then 
and 


IV/  =  panel  wind  load, 

IV.,/  —  reduced  panel  dead  load. 


The  compression   on   the  windward  bottom  chord  of  the  «/* 
panel  will  be 


^{n-n^lV-^, 


if  we  consider  that  the  inclination  of  a  lateral  rod  to  a  line  per- 
pendicular to  the  planes  of  the  trusses  is  tan  - 1  ^.  The  tension 
in  the  same  panel,  due  to  the  reduced  dead  load  alone,  is 


except  in  the  case  of  the  first  panel,  to  find  the  stress  for  which 
//j  must  be  made  equal  to  two. 


APPENDIX  /. 


the  windward  truss ; 


m  the  nearest  end  of 


m  chord  of  the  nC" 


ral  rod  to  a  line  pcr- 
in  ~  ^  T-     The  tension 

0 

load  alone,  is 


:  the  stress  for  which 


217 


Now,  if  this  tension  be  less  than  the  compression  just  found 
tlic  chord  at  the  panel  considered,  if  not  a  compression  member' 
or  If  It  be  not  externally  aided,  will  buckle ;  for  flat  bars  cannot 
ho  .died  upon,  when  acting  separately,  to  resist  compression 

Ihe  following  inequality  should,  therefore,  hold  true  :  — 

{n,  -  !)(«  _  n,  +  I)  J^-'>  „.(«  _  n,)^^^. 

H)  inspecting  the  chord  stresses  in  a  few  Pratt  truss  through 
i.ndges.  It  can  be  readily  seen,  that,  if  this  inequality  hold  true 
for  the  second  panel,  it  will  hold  true  for  all  the  others 

The  three  following  cases  are  fair  samples  of  bridges  with 
wiiKh  the  author  has  met  in  his  practice.  The  wind  pressure 
assumed  is  thirty  pounds  per  square  foot. 

('^  A  140' span  of  12' clear  roadway  is  23' deep,  consists  of 
seven  panels,  weighs  460  pounds  per  lineal  foot,  presents  to  the 
wind  about  SIX  square  feet  of  surface  below  the  middle  horizontal 
plane  for  every  lineal  foot,  and  about  eight  and  a  half  square 
feet  above  and  below.  The  centre  of  pressure  is  about  8  feet 
alx.ve  the  shoe  plate,  and  the  width  of  the  truss  is  i  foot 
These  data  give  W^  =  73,  and,  for  the  second  panel, 


W„ 


and 


(«i-0(«-«, +  i)7=xg. 


W 

«i(«  -  «i)-,    =  150. 


(2)  A  150  span  of  14' clear  roadway  is  24' deep,  consists  of 
cigh  panels,  weighs  540  pounds  per  lineal  foot,  presents  to  the 
wuK  about  six  and  a  half  square  feet  of  surface  per  lineal  foot 
lor  the  lower  lateral  system,  and  about  nine  square  feet  above 
and  below.  The  centre  of  pressure  is  about  8|  feet  above  the 
shoe  plate,  and  the  width  of  the  truss  is  about  i  foot 

1  hese  data  give  \\\  =117,  and,  for  the  second  panel, 

and  '^ 

n^\n  —  «i)-j  =  167.1. 


ft 


i8 


APPENDIX    /. 


(x\  A  1 20'  span  of  16'  clear  roadway  is  22'  deep,  consists  of 
six  panels,  weighs  530  pounds  per  lineal  foot,  and  presents  the 
same  surface  per  lineal  foot  as  in  the  last  case.    The  centre  u 
pressure  is  about  7-1  feet  above  the  shoe  plate,  and  the  width 
of  the  truss  is  I  foot. 

These  data  give  W^  =  146,  and,  for  the  second  panel, 


(«,  -  i)(« 


and 


VV 


tiiin  -  tii)-j  =  97-5- 

In  all  these  cases  ^ 

(«,  -  i)(«  -  «j  +  ^)-f  <  «i(«  -  «i)t' 

How  is  it,  then,  that  more  bridges  do  not  fail  by  the  bucklins 
of  the  bottom  chord  under  wind  pressure  ?  For  two  reasons. 
First,  the  probability  of  a  bridge  ever  being  subjected  to  a 
pressure  of  thirty  pounds  per  square  foot  over  its  whole  length 
is  very  small ;  and,  second,  that  in  a  well-built  bridge,  where  the 
joists  arc  dapped  to  the  floor  beams,  the  joists  would  take  up 
the  compression  that  would  tend  to  buckle  any  panel  of  the 

chord  except  the  first.  ,    . ,       ,         i 

In  view  of  the  fact  of  the  small  chance  that  a  bridge  has  ol 
ever  being  subjected  to  the  assumed  pressure,  it  would  be  legiti- 
mate to  trust  somewhat  to  the  stiffness  of  the  joists  in  cases 
where  ^  ry 

(«,  -  i)(«  -  «,  4-  i)  ^/'  <  «i(«  -  «i)T' 

and  not  to  make  the  chords  stiffened  throughout,  except  in  short 

'Ti^,  as  the  joists  cannot  stiffen  the  end  panels,  the  chords  in 
these  panels  should  be  proportioned  to  resist  the  compression 
due  to  the  difference  between  the  longitudinal  component  of  tht 
greatest  stress  in  the  end  lateral  rod,  including  the  initial  ten- 
sion, and  the  reduced  dead-load  stress,  whenever  the  former  .s 
in  excess  of  the  latter.  It  is  often  well,  for  the  sake  of  hot 
rigidity  and  appearance,  to  stiffen  the  chords  in  the  second 
panels  when  those  in  the  first  panels  are  stiffened. 


APPENDIX  I/. 


219 


APPENDIX    II. 


hout,  except  in  short 


and 


DEMONSTRATION  OF  FORMULA  FOR  FLOOR  BEAMS. 

Let  the  notation  be  the  same  as  given  on  p.  19,  viz.  :  — 
A ^  =  area  of  bottom  flange  in  square  inches, 
A'  —  area  of  web  in  stiiiare  inches, 
A"  =  area  lost  by  a  rivet  hole  in  square  inches, 
ly  =  the  uniformly  distributed  load  in  tons, 
Z    =  length  of  beam  in  feet  between  centres  of  supports, 
/?   -  depth  in  feet  between  centres  of  gravity  of  flanges,' 

T   =  intensity  of  working  tensile  stress  in  tons. 


The  moment  at  the  centre  of  the  beam  is  ^^.  Let  us  take 
the  centre  of  moments  at  the  middle  of  the  web,  which  will 
correspond  w.th  the  neutral  surface,  if  we  assume,  which  is 
nearly  true,  that  the  upper  and  lower  flanges  are  of  the  same 
area,  and  are  subjected  to  numerically  equal  stresses 

The  moment  of  the  load  is  resisted  by  the  sum  of  che  moments  ' 
of  the  flange  stresses  and  those  of  the  web  stresses.     The  sum  of 
the  moments  of  the  flange  stresses  is 

2{A-A")Tx~={A-A")TD. 
^  J^hej-esisting-moment  of  the  web  stresses  is  found  as  fol- 

The  resisting-intensity  of  stress  on  the  fibre   most  remote 

rom  the  neutral  surface  may  be  taken  equal  to  T;  then  that 

for  any  fibre  ^^  the  distance  .r  will  be,  by  the  common  theory 

of  flexure,  -^f.     The   stress    on    an   elementary  area   at    this 


:'A 

] 

1 

gives,  for  the  total  resisting-moment  of  the  web, 

D 


'^7>-=f[(?y- (-?)']= 


Equating-moments  gives 


APPENDIX  II. 


distance  will  then  be  ~bdx,  where  b  and  D'  are  respectively 
the  width  and  depth  of  the  web.  The  moment  of  this  stress  is 
^-I^.bdx,  integrating  which  between  the  limits 

^  D     ,     ly 

;c  =  H and 

^2  2 


bTiy 


=  \ATiy. 


=  (^A-  A")TD  ^\A'Tiy. 


If  we  put  D  for  U ,  we  will  commit  a  small  error  on  the  side  of 
safety ;  then  will 


and  therefore 


^^  =  TD{A  -  A"  +  \A'), 
A-^L       iA'  +  A" 


Q.  E.  D. 


If  M  be  the  moment  at  any  section  of  the  beam,  and  R  the 
intensity  of  stress  on  the  fibre  most  remote  from  the  neutral 
surface  at  the  same  section  when  the  beam  is  fully  loaded,  we 

can  write  the  equation 

M=ARD^-\A'RD, 

where  A  is  the  area  of  the  top  flange,  and  V  is,  as  before 
assumed,  equal  to  D;  from  which  we  have 

M 

D{ATwy 

M 


S=RA  = 


4-0 


where  .S  is  the  stress  on  the  upper  flange  at  the  section  consid- 
ered. This  last  formula  is  useful  in  determining  the  rivet 
spacing  in  the  flanges  of  built  floor  beams  and  plate  girders. 


APPENDIX  HI. 


221 


y  are  respectively 
it  of  this  stress  is 
ts 


APPENDIX    III. 


;rror  on  the  side  of 


;  beam,  and  R  the 

e  from  the  neutral 

is  fully  loaded,  we 


id  V  is,  as  before 


;  the  section  consid- 
ermining  the  rivet 
nd  plate  girders. 


METHOD  OF  FINDING  THE   LENGTH  OF  THE  LONG   DIAGONALS 
IN  A  DOUBLE-INTERSECTION   BRIDGE. 


Let 


then 

and 
or 


/=  panel  length  of  bottom  chord  =  GD  or  DB  in  the  accom- 
panying diagram, 
c  =  half  increase  of  panel  length  in  top  chord, 
d  =  depth  of  truss  between  centres  of  chords  =  AB, 
a  =  angle  between  radial  line  at  panel  point  and  perpendicular 
to  lower  chord ; 


•  -1  ^ 
«  =  sm     — , 
a 


DE:c::l:d, 
DE  =  i 


BG^.G£=.s/^^=2^^''^. 


.(LJ". 


When  the  camber  is  small,  BG  can  be  taken  equal  to  2GD 
In  triangle  A£G,  AB  and  BG  are  known,  also  angle 
ABG  =  90°  +  2«. 


if 


222 


APPENDIX  ITL 


AB  +  BG:AB-BG\:  tan  \  [i8o°  -  (90'  +  2a)]  : 

im\\_BAG-BGA'\; 


BAG-BGA  =  2tan-i 


[^Irli^'^Gs"-")} 


Again  : 

{BAG  -  BGA)  -[■{BAG  +  BGA)  =  2BAG  = 

{BAG  -  BGA)  H-  (90°  -  2a),  which  gives  BAG; 

also 

BGA  =  180°  -  {BAG  +  90°  +  2«)  =  90°  -  (BAG  +  2a)  : 

finally, 
AG=  AB  cos  BAG +  BG  cos  BGA  =  length  of  diagonal  required. 


t w 


\  \_BAG  -  BGA\  ; 

(45-.)} 


),  which  gives  BAG; 
-  i^BAG-\-z(t)\ 

of  diagonal  required. 


( i 


!:'■ 


13'    J 


ADDENDA. 


In    an   otherwise  very  favorable  review  of  this  treatise  by 

The  America..  Engineer,"  there  was  pointed  out  a  serious 

halvSr  "'"'^   attachment   of  a  floor  beam  by  Jour 

In  the  words  of  the  review,  "the  inner  loop  will  take  neirlv 
■not  quite  all  the  load  at  the  panel  point,  when  the  bridg  t 
..^t   adjusted;   and  this  not  only  becomes  constrained  iLf 

f  int:  hr"'""^  f  '""'^  ^^"^'^^  '''^''■*     The  numbe; 

1  ^  ? r        "^  ''■'  ^°"^^^"t'y  w^'-king  loose,  presum- 

ably  by  stretching,  m  railroad-bridges  in  which  this  detail  is 
used,  demonstrates  its  unsatisfactory  character  " 

The  author  has  long  recognized  the  inequality  of  distribu- 
>on  of  floor-beam  load  between  the  inner  and  outer  hangers 
but  considered  that  the  low  intensity  of  working-stress  on 
these  members  would  compensate  for  the  objectionable  in- 
"luality.  Such  has  been  also,  in  all  probability,  the  opinion  of 
most  American  engineers  ;  for  beams,  when  not  riveted  to  the 
posts,  are  nearly  always  suspended  by  four  hangers.     The  fact 

the  inner  hangers  working  loose  can  have  been  only  lately 
-vered      It  shows,  however,  that  this  detail  needs  improve' 

nt,    uKl  as    hc>  aim  of  this  treatise  is  to  design  structures 

J^^^^^^^o^tjh^^       of  so  doing  is  to  use  single  beam 


•  Main  diai;()nal. 


221; 


226 


ADDENDA. 


hangers  ;  but  this  method  will  not  always  work,  owing  to  the 
<acat  bending-movements  which  they  produce  upon  the  puis. 
For  instance,  take  the  case  of  a  20'  panel  of  a  Class  A  bridge 
having  a  24'  clear  roadway,  and  two  6'  sidewalks.  The  weight 
supported  by  each  single  hanger  would  be  about  23  tons,  and 
the  distance  between  centres  of  main  diagonals  would  not  be 
far  from  ten  inches.  These  data  give  a  vertical  bending- 
moment  upon  the  pin  equal  to  57-5  inch-tons,  which  aloue 
would  call  for  an  iron  pin  4!"  in  diameter ;  but,  when  combined 
with  the  horizontal  moment,  it  would  require  a  much  larger  pin 
than  a  practical  designer  would  care  to  employ. 

The  double  hangers  in  such  a  case  are  a  necessity,  but  the 
connection  must  be  such  as  to  distribute  the  load  eqttally  iq^on 
them.     Such  a  distribution  can  be  assured  by  using  the  follow- 

ing  detail  :  —  ,.111 

On  the  under  side  of  the  beam  at  each  end  is  attached  by 
four  rivets  a  plate  about  five-eighths  of  an  inch  thick,  six  inches 
Ion-    and  as  wide  as,  or  a  little  wider  than,  the  beam  flange, 
Th£  plate  is  placed  symmetrically  to  the  plane  of  the  truss; 
and  the  middle  of  the  under  side  is  grooved  so  as  to  receive 
one-sixth  of  the  surface  of  a  pin  about  two  inches  in  diameter, 
which  rests  in  a  similar  groove  on  the  top  of  the  beam-hanger 
plate      The  lateral  dimensions  of   this   plate  will    be    slightly 
greater  than  usual,  but  the  thickness  need  not  exceed  three- 
quarters  of   an  inch.     To  prevent  the  plate  from  rupture   by 
bending,  there  are  attached  to  the  under  side  by  countersunk 
rivets  two  angle  irons,  or  plates  bent  into  the  form  of  angle 
irons,  the  vertical  legs  being  connected  by  countersunk  rivets, 
which  in  the  neighborhood  of  the  pin  pass  as  nearly  as  may  be 

through  the  neutral  surface  of  the  T  beam,  and  elsewhere  near 

the  lower  edges  of  the  angles. 

As  the  axis  of  the  pin  is  parallel  to  the  length  of  the  bndgc 

the  vertical  legs  must  be  transverse  thereto.     This  detail  will 

be  readily  understood  by  referring  to  Plate  VIII.        _ 

To  illustrate  how  to  find  the  sizes  of  the  stiffening  plates, 

number  of   rivets  required,  etc..  let  us  design  a  beam-han^er 

plate,  when  the    total  weight   upon   the  four  hangers  is  ict. 

tons      The  centres  of  the  beam-hanger  holes  may  be  assumed 


i,  5 


ADDENDA. 


227 


to  be  situated  on  the  corners  of  a  six-inch  square.  This  would 
make  the  bending-moment  on  the  plate  thirty  inch-tons,  which 
would  be  resisted  by  the  T-shaped  section  of  the  two  bent 
pates  combined  with  the  uncut  portion  of  the  beam-hanger 
P  ate  below  the  pin.  Assuming  the  latter  thickness  i",  and 
the  plate  stiffeners  to  be  of  6"  X  6"  X  i"  angle  iron,  would 
make  the  T  about  12"  X  6f'  X  i",  the  centre  of  gravity  of 
wh.ch  ,s  about  5'  above  the  bottom.  The  moment  of  inertia 
IS,  tlierefore, 

i',  X  12  X  (i.o)'^-h  12  X  (i.o)^-hTV  X  r  X  (5.5)3 

+  5-5  X  (2.25)^  =  54-1-. 
The  resisting  moment  is  given  by  the  equation 


M  = 


d, 


so  taking  7?  =  4  tons. 


J/=1J<_14^ 


43-2. 


As  the  bending-moment  was  thirty  inch-tons,  the  sizes 
assumed  are  ample. 

It  will  be  well  to  use  three-quarter-inch  countersunk  rivets 
(the  largest  possible),  so  as  to  make  the  different  portions  of 
the  T  head  act  together. 

There  is  a  tendency  to  bend  the  plate  in  a  direction  at  rio-ht 
angles  to  the  one  considered,  the  moment  for  which  is  fifteen 
inch-f.ns  on  each  side  of  the  pin.  This  will  be  resisted  by  a 
couple  whose  forces  act  as  compression  on  the  top  plate  of  ^he 
T,  and  tension  on  the  rivets  near  the  bottom  of  the  an-les 
lakmg  the  centre  of  moments  at  the  middle  of  the  top  plate 
and  the  distance  therefrom  to  the  horizontal  centre  line  of  the 
nvetj^ioles  as  4!  inches,  will  make  the  tension  on  the  rivets 
i,i'?  —  3.42  tons.  Using  an  intensity  of  only  two  and  a  half 
tons,  because  of  the  initial  tension  on  the  rivets,  will  make  the 
section  required  1.37  square  inches:  consequently  two  i"  rivets 
will  be  sufficient. 


l!  1 1 


J! 
11 


228 


ADDENDA. 


The  difference  in  the  total  weight  of  iron  per  hneal  foot 
caused  by  the  use  of  this  detail  will  be  from  six  to  ten  pound., 
which  weight  should  be  added  to  those  given  in  Tables  I  II., 
Tnd  III.,  under  the  heading  "Floor  System/'  whenever  this 
style  of  beam-hanger  plate  is  to  be  employed 

It  will  be  noticed  in  the  diagram  on  Plate  V  II.,  that  the 
floor-beam  stiffeners  at  the  support  are  placed  close  together 
so  as  to  take  up  the  vertical  reaction  of  the  hangers  transferred 
by  the  auxiliary  pin.  The  sectional  area  of  these  stiffeners 
should  be  about  equal  to  that  of  the  hangers. 

Plate  VIII    illustrates  a  detail   by  which  the  foot  of  a  pes 
may  be  riveted  or  bolted  to  the  floor  beam,  for  the  purpose  of 
aiding  the  distribution  of  lower  lateral  rod  stresses  among  the 
chord  bars.     This  is  accomplished  by  means  of  a  jaw  plate  be- 
tween the  post  channels,  and  by  turning  up  the  ends  of  the 
exterior   re-enforcing    plates,   so  as   to  permit  the  passage  0 
rivets  or  bolts.     The  latter  may  be  considered  pre  erabc , 
they  need  not  be  screwed  up  very  hard,  but  should   ht  with 
.rcat  accuracy  in  the  holes.      Their  object  is  to  prevent  tor- 
^ion  of  the  post,  but  not  to  aid  the  beam  hangers  in  resisting 

^'^  When  this  detail  is  employed,  the  lower  chord  pin  at  the  first 
panel  point  should  pass  through  holes  bored  in  bent  plates,  which 
are  to  be  well  riveted  to  the  floor  beam.  _ 

It  is  probable  that  most  bridge  designers  wdl  consider  this 
arran-^ement  to  possess  too  much  refinement  for  highway- 
bridges,  preferring  to  trust  to  the  rigidity  of  the  joists  as  sug- 

^^'¥here'is'no'  doubt,  though,  about  its  being  a  detail  that  could 
be  advantageously  employed  in  railroad-bridges. 

When  ve>rtical  sway  bracing  is  used,  the  detail    or  t  e  upper 
lateral  strut  connection,  shown  on  Plate  VIII.,  will  be   oun 
be  an  improvement  on  the  one  previously  described,  in  that  it 

obviates  field  riveting.  .,  1  „f  ti^A 

It  consists   in  the  use  of  a  double  ]aw  on  the  end  of  t 
lateral  strut,  and  two  nuts  of  different  diameters  the  pin  be  n 
aoubly  shouldered.     The  office  of  the  inner  and  larger 
to  press  the  end  of  the  strut  against  the  chord  ;  and  that  of 


■  I   I 


ADDENDA. 


229 


the  outer  one,  to  take  up  the  pull  of  the  bent  eyes,  the  injuri- 
ous  effect  of  which  is  mitigated  by  the  inner  jaw  plate. 

When  no  vertical  sway  bracing  is  used,  the  detail  described 
on  p.  98  will  probably  be  preferable  ;  because  it  involves  the 
spreading  apart  of  the  lateral  strut  channels,  and  thus  furnishes 
a  greater  resistance  to  bending  the  strut.  The  use  of  the  im- 
pr()^•cd  detail  will  not  affect  the  sizes  of  the  lateral  strut  chan- 
nels as  given  in  Table  XXV. 

Plate  VIII.  illustrates  also  an  improved  connection  for  the 
portal  struts,  avoiding  the  necessity  for  field  riveting.  The 
increased  depth  of  the  jaw  plate  at  the  pin  hole  is  an  impor- 
tant feature,  its  object  being  to  resist  the  bending  effect  of  that 
component  of  the  stress  in  the  portal  rods  which  is  parallel  to 
the  length  of  the  batter  brace. 

Whenever  the  portal  rods  exceed  ij"in  diameter,  this  im- 
proved  shape  of  jaw  plate  should  be  employed. 


n\ 


n 


M 


GLOSSARY  OF  TERMS. 


'It  Ml 


GLOSSARY  OF  TERMS. 


Adjustable  Member.  — A  member  of  a  bridge  the  length  of  which  can  be 
iiK K  asrd  or  iliniinishcd  at  will. 
Angle  Iron.  — Iron  rolled  into  the  shape  shown  in  section  on  Plate  II 

Apex.  — The  intersection  of  a  brace  with  a  chord  or  flange;  called  al.so  a 
paiK'l  point. 

Axis  of  Symmetry.  —  A  line  dividing  an  area  into  two  parts  equal  and 
.similar  to  each  other,  and  similarly  di.sposed  to  the  line. 

Bar. —  A  piece  of  iron  flat  or  square  in  .section. 

Batter.  —  Slope,  or  inclination,  to  the  vertical;  usually  measured  by  the 
tan^aiit  of  the  angle,  or  so  many  inches  to  the  foot. 

Batter  Brace.  — The  inclined  end  post  of  a  bridge.     (Plate  I.) 

Beam.  — A  member  intended  to  resist  bending. 

Beam  Hanger.  —  A  rod  or  square  bar  supporting  a  floor  beam  from  a 
clion!  pin.    (Plate  I.  and  Plate  II.,  Fig.  13.) 

Beam-hanger  Nuts.  -  Nuts  on  the  ends  of  beam  hangers,  serving  to  press 
the  tl(,or  beam  against  the  feet  of  the  posts  or  against  the  chord  heads 
(Plate  II..  Fig.  13.) 

Beam-hanger  Plate.  -  A  plate  placed  beneath  the  end  of  a  floor  beam  for 
thu  iRaiii-luinger  nuts  to  rest  against.     (Plate  JI.,  l"ig.  13.) 
Beam-trussing  Posts.  —  Posts  for  trussing  beams.     (Plate  II.,  Fig.  16.) 
Beam-trussing  Rods.— Diagonal  rods  for  trussing   beams,     (pfate   II. 

Fitr.  if).)  ' 

Bearing.  —  A  resting-place,  usually  for  a  pin  or  rivet. 
Bearing- Pressure.  —  The  pressure  on  a  bearing. 

Bed  Plate.  —  A  plate  to  distribute  pressure  upon  masonry.     (Plate  III ) 
Bending-Moment.  _  The  moment  of  a  force  or  forces  which  bend  or  tend 
to  bend  a  piece. 

Bending-Stress.  — The  stress  produced  in  a  piece  by  bending. 
Bent.  _  A  frame  of  timber  or  iron,  usually  the  former,  as  a  bent  of  false- 
work. 

Bent  Eye.  — An  eye  on  the  end  of  a  bar,  the  plane  of  which  makes  an 

angle  with  the  direction  of  the  length  of  the  bar. 
Bevel.  _  The  slope  on  the  end  of  a  piece. 

2,n 


'^i 


III* 


m 


234 


GLOSSA/^V   OF    TEM.IfS. 


Bill  of  Material.  —  A  list  of  various  portions  of  material  giving  dimensions 
and  weights,  or  other  quantitative  measurements. 

Block. —A  system  of  one  or  more  pulleys  or  sheaves,  so  arran^^d  in  a 
frame  or  shell  as  to  multiply  the  power  of  the  rope  passing  around  tlieni,  or 
to  change  its  direction. 

Board  Measure.  — The  measure  of  timber,  the  unit  being  a  piece  one  foot 
square  and  one  inch  thick.  Timber  is  sold  at  so  much  per  thousand  feut 
board  measure,  usually  written,  per  M.  b.  m. 

Bolt.  —  An  iron  rod  with  a  square  head  at  one  end,  and  a  thread  and  nut  at 

the  other . 

Brace.  — Generally  a  strut,  but  sometimes  the  term  is  applied  to  a  tie. 

Bracket.  —  A  knee  or  knee  brace  to  connect  a  post  or  batter  brace  to  an 
overhead  strut.     (I'late  I.  or  Plate  II.,  Fig.  i2.) 

Built-Beam.  —  A  beam  made  up  of  plates  and  angles  riveted  together. 

(I'late  II.,  Fig.  13-) 

Burr.  —  A  rough  edge  or  ridge  left  l)y  a  tool  in  cutting  metal.  The  term 
is  sometimes  used  for  a  nut. 

Button  Sett.  —  A  tool  for  forming  the  heads  of  rivets. 

Camber.  —  The  upward  curvature  of  a  truss.  It  is  measured  by  the  heigiit 
of  the  middle  point  of  tlie  centre  line  of  the  lower  chord  above  the  line 
joining  the  centres  of  end  pins. 

Camber  Blocks.  —  Blocks  of  wood  used  in  erection,  so  placed  as  to  be 
easily  removed      (Flate  VII.) 

Cape  Chisel.  —  A  tool  for  cutting  iron.  It  consists  of  a  rounded  edge  on 
the  end  of  a  sliort  rod.     The  edge  is  very  obtuse,  so  as  not  to  break  easily. 

Centre  of  Gravity.  —  That  point  of  a  body  about  which  the  weights  of  pll 
the  different  portions  I)alance. 

Channel,  or  Channel  Bar.- Iron  rolled  into  the  shape  shown  in  section 
on  I'late  11..  Fig.  i. 

Check  Nut,  or  Lock  Nut.  —  A  contrivance  to  prevent  a  nut  from  turning 

when  sul)jected  to  shock. 

Chord.  —  The  upper  or  lower  part  of  a  truss,  usually  horizontal,  resisting 
compression  or  tension.     (I'late  1.) 

Chord  Bar. —  A  member  of  the  chord  which  is  sul:)jected  to  tension. 
(I'late  I.) 

Chord  Head.  —  The  enlarged  end  of  a  chord  bar,  through  wliich  the  pin 

passes. 

Chord  Packing.  — The  arrangement  of  the  bottom  chord  of  a  truss. 

Clear  Headway. —  The  vertical  distance  from  the  upper  surface  of  the 
floor  to  the  lowest  part  of  the  overhead  bracing.  It  is  a  measure  of  tlie  licigiit 
of  the  highest  vehicle  that  could  pass  through  th-  bridge. 

Clear  Roadway.  —  The  horizontal  distance,  measured  perpendicularly  to 
the  planes  of  the  trusses,  between  the  inner  edges  of  the  batter  l)races.  It 
is  a  measure  of  the  width  of  the  widest  vehicle  that  could  pass  llirougli 
the  bridge. 


..ii: 


GLOSSARY'   OF    TE/iAfS, 


235 


aterial  giving  dimensions 


i,  and  a  thread  and  nut  at 


:tion,  so  placed  as  to  be 


Cleat — A  narrow  strip  of  wood  nailed  to  something  for  the  purpose  01 
kwwwr  a  piece  of  work  in  its  proper  place. 

Co-efficient  of  Friction.  -  A  numerical  quantity,  which,  multiplied  into 
the  normal  pressure,  gives  the  frictional  resistance.  It  is  equal  to  the  natural 
tangent  of  the  angle  of  repose. 

Cold  Chisel.  —  A  tool  for  cutting  iron. 

Column.- A  pillar  or  strut;  a  long  member  which  resists  compression 

Component. -One  of  the.  parts  into  which  a  stress  may  be  resolved 'or 
divided. 

Compression. -A  stress  which  tends  to  shorten  the  member  which  is 
siilijccted  to  It. 

Concentrated  Load.  _  A  load  which  is,  or  may  be  considered,  collected  at 

one  or  more  points. 

Connecting  Chord  Heads. -Chord  heads  used  to  connect  bottom  chord 
channels  to  pms.     (Plate  II.,  Fig.  10.) 
Connecting-Plate.- A  plate!ised  for  connecting  two  pieces 
Contmuous  Spans. -Consecutive   spans   connected   over   the   points   of 

support. 

Counter. -An  adjustable  diagonal  which  is  not  subjected  to  stress  bv  a 
uniloimly  distributed  load  covering  the  bridge.     (Plate  1 ) 

Countersunk  Rivets.- Rivets,  the  heads'of  which  are  let  into  one  or  both 
of  the  plates  which  they  connect,  so  as  to  leave  a  Hush  surface  or  surfaces 

Couple.  —  Two  equal  and  parallel  forces  not  acting  in  the  same  line. 

Cover  Plate.- A  plate  used  to  cover  a  joint,  or  to  connect  two  pieces  of 
the  top  chord  plate,     (llate  11.,  Figs.  11  and  12.) 

Crab. -A  slow-motion  machine,  worked  by  a  crank  for  the  purpose  of 
winding  a  rope  x\\Mm  a  drum,  thereby  raising  a  heavy  weight. 

Dap.— To  notch  timber  onto  its  bearing. 

Dead  Load. -The  weight  of  all  the  parts  of  the  bridge  itself,  and  any 
thing  tiiat  may  remain  upon  it  for  any  length  of  time. 

Deck  Bridge.- A  JM-idge  in  which'the  passing  loads  come  upon  the  upper 
chords  or  the  upper  ends  of  the  jiosts. 

Deflection. -Motion  laterally,  or  at  right  angles  ro  the  length  of  the  piece 
it  IS  also  used  for  the  amount  of  motion,  and  is  generally  expressed  in  inches 

Depth  of  Truss. -The  vertical  distance  between  the  centre  lines  of  upper 
and  lower  chords.  ' 

Diagonal.  —  A  member  running  obliquely  across  a  panel.  In  this  work  all 
the  (ha-onals  except  the  batter  braces  are  tension  members. 

Diagram  of  Stresses. -A  skeleton  drawing  of  a  truss,  upon  which  are 
wrm,  II  the  stresses  in  the  different  members.     (Plate  V  ) 

Double  Intersection. -The  style  of  truss  where  the  diagonals  cross  the 
posts  at  the  middle  of  their  length,  as  in  the  bridge  shown  on  Plate  1 

Double-riveted  Lacing.  _  Lacing  in  which  each  bar  is  connected  by  two 
"vets  at  each  end,     (Plate  11.,  Fig.  13,) 


236 


GLOSSARY   OF    TERMS. 


I  I 


■^f  \[ 


Drift  Bolt.  —  A  round  or  square  piece  of  iron,  usually  from  one  to  three 
feet  long,  without  head  or  nut,  used  to  connect  timbers. 

Drift  Pin.  —  A  slightly  tapering  rod  of  hard  steel,  used  for  making  rivet 
holes  coincide.     Its  use  is  more  convenient  than  advisable. 

Effective  Area.  —  The  gross  area  of  a  section,  less  that  lost  by  rivet  or 
pin  holes;  the  net  area. 

Elastic  Limit.  —  That  intensity  of  stress  at  which  the  ratio  of  stress  over 
strain  commences  to  show  a  decided  change.  .  For  wrought-iron  it  is  from 
twelve  to  fifteen  tons. 

Erecting-Bill.  —  A  bill  of  material  for  a  bridge,  so  arranged  as  to  facilitate 
the  finding  and  placing  of  members  during  erection. 

Expansion  Joint.  — The  connection  of  pedestal  to  bed-plate,  shown  on 

Plate  111. 

Expansion  Rollers.  —  A  set  of  half  a  dozen  or  more  turned  rods  of  exactly 
the  same  diameter,  placed  under  the  shoe  plate  at  one  end  of  a  truss  to 
permit  of  expansion  and  contraction.     (Plate  II.,  Fig.  9.) 

Extension  Plate.  —  A  jjlate  riveted  to  the  end  of  a  strut  channel,  and  pro- 
jecting beyond  it,  to  permit  of  the  passage  of  a  pin.     (Plate  II.,  Fig.  12.) 
Eye.  —  A  hole  in  the  end  of  a  member  to  permit  of  the  passage  of  a  pin. 
Eye  Bar.  —A  bar  with  an  eye  at  each  or  one  end. 

Factor,  or  Factor  of  Safety.  —Tlie  ratio  of  ultimate  load  to  greatest  allow- 
able working-load.  This  term  is  getting  out  of  favor  among  engineers,  as  its 
use  has  been  somewhat  abused.  There  is  no  such  thing  as  a  factor  of  safety 
for  a  well-proportioned  bridge,  for  each  member  should  have  an  intensity  of 
workinc-stress  proportionate  to  the  character  and  amount  of  work  which  it 
has  to  perform. 

Fall  Line.  — A  rope  used  in  erection  for  raising  and  lowering  weights. 

Falsework.  —  Temporary  timber  work  to  support  a  bridge  during  erection. 

Felly  Plank.  —  A  guard  rail  so  placed  as  to  catch  the  felly  of  a  wheel,  and 
thus  prevent  the  vehicle  from  striking  the  truss.  (Plate  II.,  Fig.  13.)  In 
wide  bridges  a  felly  plank  is  often  placed  midway  between  the  trusses,  to 
prevent  vehicles  passing  from  one  side  of  the  bridge  to  the  other. 

Field  Riveting.  —  Riveting  done  in  the  field,  or  during  erection.  It  is  the 
poorest  and  most  expensive  kind  of  riveting. 

Fixed  End.  —  An  end  of  a  strut  so  firmly  connected  as  to  prevent  all  motion 
of  the  strut  in  the  neighborhood  of  the  end. 

Filling- Plate.  —  A  plate  tlie  function  of  which  is  to  make  flush  two  surfaces 
(Plate  II.,  Fig.  12.) 

Filler. —  A  small  ring  of  iron  or  piece  of  ])ipe  placed  on  a  pin  in  order  to 
keep  in  position  the  members  coupled  thereon. 

Fixed  Load.  —  A  load  remaining  i)ormanently,  or  for  a  considerable  length 
of  time,  upon  a  structure  or  portion  of  h  structure. 

Flange.  —  The  upi)er  or  lower  chord  of  a  beam.  It  is  the  principal  part 
for  resisting  either  compression  or  tension. 

Flexure.  —  Bending. 


GLOSSARY   OF    TERMS. 


217 


)  arranged  as  to  facilitate 


to  bed-plale,  sliown  on 

re  turned  rods  of  exactly 
t  one  end  of  a  truss  to 


Floor,  or  Flooring.  —  That  part  of  the  bridge  which  directly  receives  the 
tr;v>rl.     (Plate  II.,  Fig.  13.) 

Floor  Beam.  —  A  beam  to  support  a  portion  of  the  floor  and  its  load. 
ll'latu  1.  and  J'late  II.,  f^ig.  13.) 

Forge.  —  An  apparatus  for  heating  iron. 

Framing The  carpenter  work  on  timber. 

Giasticutus  Rods.  —  A  term  (perhaps  unauthorized,  but  in  common  use 
aiiiimg  Imdge  builders)  to  denote  a  small  horizontal  rod  connecting  the  middle 
points  of  two  adjacent  posts  of  the  same  truss,  for  the  professed  purpose  of 
lixinu  or  holding  the  posts  at  the  middle  in  order  that  they  may  be  figured 
for  halt-length.     The  benefit  derived  therefrom  is  more  imaginary  than  real. 

Girder —  Any  structure  to  cross  a  chasm  or  opening.  The  term  is  gener- 
ally applied  to  short  structures  for  places  where  it  is  not  advisable  to  use 
trusses:  for  instance,  a  plate  girder,  or  a  rolled  girder. 

Guard  Rail.  —  See  felly  plank. 

Guys,  or  Guy  Lines.  —  Lines  for  bracing  the  top  of  a  pole,  derrick,  or  any 
simihir  apparatus. 

Gyration — See  radius  of  gyration. 

Hammered  Head.  —  A  head  formed  on  the  end  of  a  bar  by  hammering. 

Hand  Lines.  —  Small  ro])es  used  in  erection. 

Hand  Rail,  or  Hand  Railing.  —  An  iron  or  wooden  frame  placed  on  or 
near  the  outside  of  a  bridge  in  order  to  prevent  persons  or  animals  from 
lalliiiu'  therefrom.     (Plate  IV.,  or  Plate  II.,  Fig.  13.) 

Hand-rail  Cap.  —  The  upper  longitudinal  timber  or  timbers  of  a  wooden 
liand-railing.     (Plate  II.,  Fig.  13.) 

Hand-rail  Post.  —  Post  for  supporting  a  hand  railing.  (Plate  II.,  Fig.  13  ; 
Plate  IV.) 

Headway.  —  See  clear  headway. 

Hinged  End.  —  An  end  of  a  strut  connected  only  by  a  pin. 

Hip. —  The  jjlace  at  which  the  top  chord  meets  the  batter  brace. 

Hip  Joint.  —  The  joint  of  the  top  chord  and  batter  brace. 

Hip  Vertical.  —  A  rod  hung  from  the  pin  at  the  hip  for  the  purpose  of 
^^ls]n  iiding  the  floor  beam. 

Holding-on  Bar.  —  \  lever  to  hold  against  one  end  of  a  rivet  while  the 
liuh!  at  the  other  end  is  being  formed  with  a  button  sett. 

Hub  Plank.  —  A  plank  to  protect  the  iron-work  of  the  truss  from  being 
strink  by  the  hubs  of  passing  wheels.     (Plate  II.,  Fig.  13.) 

I-Beam.  —  A  piece  of  rolled  iron  of  the  section  shown  ow  Plate  II.,  Fig.  2. 

Initial  Tension — The  tension  caused  in  any  adjustable  member  by  screw- 
ing; lip  the  adjusting  apparatus. 

Intensity.  —  Tiie  intensity  of  a  stress  is  the  amount  of  stress  upon  a  square 
iiuli  (il  section. 

Intermediate  Strut.— An  overhead  strut  in  high  bridges,  attached  to  the 
posts  (it  ()p])osite  trusses,  and  lying  between  the  upper  lateral  strut  and 
llic  ilcxir.  In  deck  bridges,  if  used  at  all,  it  would  lie  between  the  upper 
and  hnvcr  lateral  struts.     (Plate  I.) 


ittiiii 


If 


« 


238 


GLOSSARY   OF   TEIUfS. 


Jaw.  —  A  connection  on  the  end  o£  a  strut  similar  to  that  shown  on  Plate 
II.,  Fig.  13. 

Joint. —  A  place  where  two  alnitting  or  lapping  pieces  are  connected. 

Joist.  —  A  timlier  l)eam  that  supports  part  of  the  Hoor  and  its  load.  (Plate  I. 
and  Plate  II.,  Fig.  13) 

Knee,  or  Knee  Brace See  bracket. 

Lacing.  —  A  system  of  l)ars,  not  intersecting  each  other  at  the  middle,  used 
to  connect  the  two  channels  of  a  strut  in  order  to  make  them  act  as  one 
member.     (Plate  II.,  Fig.  12.) 

Lacing-Bar A  bar  belonging  to  a  system  of  lacing. 

Lateral  Rod.  —  A  tension  diagonal  of  a  lateral  system.     (Plate  I.) 

Lateral  Strut.  —  A  compression  member  of  a  lateral  system.     (Plate  I.) 

Lateral  System.  —  A  system  of  tension  and  compression  members  forming 
the  we!)  of  a  horizontal  truss  connecting  the  opposite  chords  of  a  bridge.  Its 
puri^oses  are  to  transmit  wind  pressure  to  the  piers  or  abutments,  and  to 
prevent  undue  vibration  from  jjassing  loads. 

Latticing.  —  A  system  of  bars  crossing  each  other  at  the  middle  of  their 
lengths,  u.sed  to  connect  tiie  two  channels  of  a  strut  in  order  to  make  them 
act  as  one  member.     (Plate  II.,  Fig.  12.) 

Lattice  Bar.  —  A  bar  belonging  to  a  system  of  latticing. 

Leg.  —  One  of  the  two  portions  of  an  angle  iron  separated  from  each  other 
by  the  bend. 

Lever  Arm.  —  The  perpendicular  from  the  centre  of  moments  to  the  line 
of  action  of  a  force.  The  lever  arm  of  a  couple  is  the  perpendicular  distance 
between  the  lines  of  action  of  the  two  equal  and  parallel  forces. 

Live  Load. —  The  moving  or  passing  load  upon  a  structure. 

Linville  Truss  (also  called  "  Double  Ouadrangular,"  "  Whipple,"  and 
"  Double  .System  Pratt "  truss).  —  A  truss  with  vertical  posts  and  diagonal 
ties  spanning  two  panels.     It  is  the  truss  represented  on  Plate  I. 

Lock  Nut.  —  See  check  nut. 

Loop  Eye.  —  .In  eye  on  the  end  of  a  rod  or  square  bar,  elongated  into  the 
form  of  a  loop,  as  shown  on  Plate  II.,  Fig.  16. 

Lower  Falsework.  —  The  falsework  below  the  level  of  the  lower  chords. 

Main  Diagonal.  —  A  tension  member  of  a  truss,  sloping  uinvard  towards 
the  nearer  end  of  the  sjian.  Main  diagonals  in  iron  bridges  are  not  adjust- 
able. 

Moment.  —  The  [jroduct  of  a  force  by  its  lever  arm. 

Moment  of  Inertia.  —  Represented  by  the  equation,  /  -  Ap'^  =  Zr'-dA, 
where  //  is  the  area  of  the  section  considered,  p  the  radius  of  gyration,  ■.\w\r 
the  distance  of  any  point  from  an  assumed  line  lying  either  in  the  surtace  or 
outside  of  it:  in  other  words,  the  moment  of  inertia  of  a  surface  about  any 
a.xis  is  the  product  of  the  area  by  the  square  of  the  radius  of  gyration  ;  or 
it  is  the  summation  of  the  products  of  each  differential  of  the  area  l>y  tlie 
sc^uare  of  its  distance  from  the  axis.  If  the  axis  lie  in  the  surface,  the 
moment  of  inertia  is  called  a  surface  moment  of  inertia;  while,  if  the  axis 


tttJili 


ii 


GLOSSARY   OF   TERMS. 


239 


r  to  that  shown  on  Plate 


.re  bar,  elongated  into  the 


be  perpendicular  to  the  surface,  the  moment  of  inertia  is  called  a  polar 
moment  of  inertia. 

Monkey  Wrench.  —  A  wrench  capable  of  being  adjusted  so  as  to  fit  nuts 
of  (lilt'erent  sizes. 

Moving  Load.  —  See  live  load. 

Mud-Sill.  —  A  timber,  usually  from  6"  by  6"  to  12"  by  12",  at  the  bottom 
of  a  i)C'nt.  It  is  laid  horizontally  in  a  trench,  and  the  posts  of  the  bent  rest 
upon  it. 

Name  Plate.  —  A  plate  of  iron  placed  in  a  conspicuous  position  on  a 
l)ii(ls,'e.  containing  the  name  of  the  maker  or  designer  of  the  structure. 

Negative  Rotation.  —  Rotation  in  a  direction  opposite  to  that  of  the  hands 
of  a  watcli. 

Net  Section.  —  See  effective  area. 

Neutral  Surface.  —  That  part  of  a  member  subjected  to  bending,  which  is 
iitithLT  extended  nor  compressed.  In  symmetrical  wrought-iron  beams,  with 
equal  or  nearly  equal  flanges,  it  is  taken  to  be  at  the  centre  line  of  the  web. 

Nut.  —  A  small  piece  of  iron  with  a  threaded  core  to  fit  on  the  screw  end 
of  a  bolt,  rod,  or  bar.     (Plate  II.,  Fig.  6.) 

Order  Bill. —  A  form  of  bill  used  in  ordering  material  from  the  manufac- 
tuiTrs. 

Ornamental  Work.  —  Fancy  work  at  the  portals  of  a  bridge  to  give  it 
airhilccturnl  effect.     (I'lates  I.  and  VI.) 

Overhead  Bracing.  —  The  upper  lateral  or  vertical  sway  bracing  in 
tlir()u;,'h  bridges.  The  term  is  usually  applied  to  the  vertical  sway  bracing, 
if  tlicre  be  any ;  if  not,  to  the  upper  lateral  bracing. 

Packing.  —  See  chord  packing. 

Panel.  —  That  portion  of  a  truss  between  adjacent  posts  or  struts  in  Pratt 
tiu.--s  bridges;  called  also  a  bay. 

Panel  Length. — The  distance  between  two  adjacent  ])anel  points  of  the 
.-laiiio  ciiord. 

Panel  Point See  ape.x. 

Pedestal.  —  The  foot  of  a  batter  brace  or  end  post.     (Plate  II.,  Fig.  9.) 

Permanent  Set.  —  The  alteration  in  length  of  a  piece  of  material  which  has 
liein  ^ui>jected  to  stress,  remaining  after  the  stress  has  been  rem  ;ved. 

Pillar.  —  See  column. 

Pilot  Nut,  or  Pin  Pilot.  —  A  nut,  one  end  of  which  is  a  truncated  cone, 
used  to  ])rotect  the  thread  on  tlie  end  of  a  pin  when  the  latter  is  being  driven 
into  place.    (Plate  II.,  Fig.  5.) 

Pin.  —  A  cylindrical  piece  of  iron  used  to  connect  bridge  members.  (Plate 
11 .  i'ig,  5.) 

Pitch.  —  The  distance  between  centres  of  consecutive  rivets  of  the  same 


Plane  of  Symmetry.  —  A  plane  tlividing  a  body  into  two  equal  and  sym- 
iiutiiial  i)arts  similarly  disposed  in  reference  to  the  plane. 
Plant.  — Tools  and  apparatus  useil  in  construction. 


!      I     i 


240 


GLOSSARY   OF   TERMS. 


H  '  f 


Plate.  —  A  piece  of  flat  iron  wider  tlian  a  bar.  Tlie  common  distinction 
between  the  two  is  that  a  plate  is  attached  to  something  else,  and  acts  witii  it, 
while  a  bar  is  an  independent  member. 

Plate  Girder. —  A  beam,  built  of  plates  and  angles,  used  to  span  a  small 
opening,  generally  less  than  forty  feet. 

Pony  Truss.  —  A  truss  so  shallow  as  not  to  permit  the  use  of  overhead 

bracing. 

Portal. —  The  space  between  the  batter  braces  at  one  end  of  a  bridge. 
Sometimes  the  term  is  applied  to  the  portal  bracing,  though  incorrectly. 

Portal  Bracing.  —  Tiie  combination  of  struts  and  ties  in  the  plane  ot  tlie 
batter  braces  at  a  portal,  which  transfers  the  wind  pressure  from  the  upper 
lateral  svstem  to  the  abutment  or  pier. 

Portal  Strut.  — A  strut  belonging  to  the  portal  bracing.     (Plate  I.) 

Positive   Rotation.  —  Rotation  in  the  direction  of  the  hands  of  a  watch. 

Post.  —  A  vertical  strut.     (Plate  I.) 

Pratt  Truss  (called  also  the  "  Murphy-Whipple,"  or  "Quadrangular" 
truss;.  —  A  single-intersection  truss  with  vertical  struts  and  diagonal  ties. 

Quadrangular  Truss.  —  See  Pratt  truss. 

Radius  of  Gyration.  —The  radius  of  gyration  of  any  surface  in  reference 
to  an  axis  is  ;he  distance  from  the  a.xis  to  that  point  of  the  surface  in  which, 
if  the  whole  area  were  concentrated,  the  moment  of  inertia  in  reference  to  thu 
axis  would  be  unchanged.  It  is  therefore  equal  to  the  square  root  of  the  ratio 
of  the  moment  of  inertia  over  the  area. 

Ream.  —  To  enlarge  a  rivet  hole. 

Reamer.  —  A  tool  for  enlarging  rivet  holes. 

Re-enforcing  Plate.  —  A  jtlate  used  for  the  purpose  of  providing  additional 
pin  l)earing,  or  strength,  to  compensate  for  material  cut  away.  (Plate  11., 
Figs.  1 1  and  13.) 

Resolve.  —  To  divide  a  force  into  component  parts. 

Rivet.  —  A  short  piece  of  round  iron  tightly  connecting  two  or  more  thick- 
nesses of  metal,  and  having,  when  in  place,  a  head  at  each  end. 

Roadway.  —  The  passage-way  of  a  bridge  for  vehicles ;  usually  means 
clear  roadway,  q.  v. 

Rod.  —  A  piece  of  round  iron. 

Rolled  Beam.  — An  J-beam.     (Plate  II.,  Fig.  2.) 

Roller.  —  See  expansion  roller. 

Roller  Frame.- A  light  frame  of  iron  for  holding  the  rollers  in  position. 
(Plate  II..  Fig.  9.) 

Roller  Plate.  — The  plate  upon  which  the  rollers  rest,  and  which  itself  rcs^ 

upon  the  masonry. 

Rope  Sling.  —  See  sling. 

Run.  —  A  line,  or  string;  as,  a  run  of  joists. 

Set.  —  The  extension  or  compression  of  a  piece  of  material  under  stress. 

Shear,  or  Shearing-Stress.  —  The  resistance  which  a  body  offers  to  the 
])assage,or  to  the  tendency  to  passage,  of  one  section  along  the  next  consecu- 
tive section. 


GLOSSARY    O/--    TKKMS. 


241 


Shipping-Bill. —  A  list  of  portions  of  a  bridge,  arranged  in  a  manner  to 
f;uilitate  counting  and  chucking  when  tlie  material  is  received  after  shipment. 

Shoe.  —  Another  term  for  pedestal,  q.  v. 

Shoe  Plate.  — The  plate  on  the  under  side  of  the  shoe,  resting  on  the 
rollers,  l)ed-i)late,  or  masonry. 

Side  Bracing.— A  bracing  for  pony  trusses  to  attach  the  panels  of  the  top 
chord  to  the  floor  beams  prolonged,  in  order  to  fix  the  panel  points  of  the 
top  chord.     (Plate  111.) 

Sidewalks.-  Roadways  at  the  sides  of  a  bridge  for  foot-passengers  on,y. 

Single  Intersection.  — That  style  of  truss  in  which  the  diagonals  do  not 
ao>s  the  posts.     It  is  rejjresented  in  skeleton  on  Plate  V. 

Skeleton  Drawing.— A  drawing  which  shows  only  the  centre  lines  of 
in(iii!'(.r.s.  such  as  a  diagram  of  stresses.     (Plate  \ ) 

Skew  Bridge.- A  bridge  in  which  the  horizontal  lines  joining  correspond- 
in-  panel  points  of  the  opposite  trusses  are  oblique  to  the  planes  of  the  trusses. 

Sledge A  heavy  hammer,  or  mallet. 

Sleeve  Nut.  — An  elongated  nut,  the  core  at  one  end  having  a  right-hantl 
ihrLmI,  and  that  at  the  other  a  left-hand  thread.  Its  office  is  to  lengthen  or 
sh(irt-n  a  tension  member.     (Plate  II.,  Fig.  16.) 

Sling.  — A  loop  of  rope,  very  useful  in  erection  for  making  a  hasty  attac  h- 
nuTit. 

Slope. —  Inclination  to  a  horizontal  plane. 

Snatch  Block. —  A  block  with  one  side  capable  of  being  opened  for  the 
insertion  of  the  rope.     Its  office  is  to  change  the  direction  of  the  rope. 

Span.  — The  length  of  a  bridge  from  centre  to  centre  of  entl  pins  or 
licarin^s. 

Spikes.  —  Large  nails  for  timber  work.    (Plate  1 1.,  Fig.  13.) 

Splay.  —  To  spread  at  one  end  the  two  main  portions  of  a  member. 

Splice.  —  A  joint  connected  by  means  of  plates. 

Splice  Plate.  — .A  connecting  jjlate  at  a  joint.     (Plate  II.,  Fig.  12.) 

Spread.  — The  distance  ajiart  laterally. 

Staggered  Rivets.—  Rivets  are  said  to  be  staggered  when  each  rivet  of  one 
row  is  opposite  to  the  middle  of  the  s])ace  between  two  rivets  of  the  next  row. 

Static  Load.  —  Dead  load.  q.  v. 

Stay  Plate.  — A  plate  always  used  at  the  end  of  a  system  of  lacing  or 
latticing.    (Plate  II..  Fig.  12.) 

Stiffening- Angle.  — .An  angle  iron  used  to  stiffen  the  web  of  abeam.  (Plate 
11..  i'iv'.  I3'l 

Stiffener.  —  A  piece  of  iron  used  to  stiffen  the  web  of  a  beam  :  it  may  be  of 
an^'lc  or  tee  section.     (Plate  II.,  Fig.  13.) 

Strain. —  The  extension  or  comjiression  of  a  piece  of  material  which  is  or 
lias  been  under  stress. 

Stress.  — The   internal   resisting  force  of   a  piece  of   material  wiiich   is 

.•-trainnl. 

Strut.  —  ,\  member  which  resists  compression. 


■JAl 


(//.(AS-.V./AM'    ('/■•     /rh'MS. 


Sub-Punching.  —  Tlic  punchinj;  of  livcl  lioks  wluil)  liavc  to  hu  afterwards 
vnlaij^ed  by  roaming. 

Sway  Bracing.  — Bracing  transverse  to  tiie  i)lanes  of  tlie  trusses,  lis 
ol)ject.s  are  to  resist  wind  pressure,  and  to  prevent  undue  vibration  fn.in 
parsing  loads,     (i'late  1.) 

Table  of  Data.  —  .\  list  of  the  known  circumstances  that  affect  the  design- 
iiig  of  a  structure. 

Tap.  —  .\  screw  for  cutting  a  thread  in  a  nut. 

Tee  or  T  iron.  — A  piece  of  rolled  iron  of  the  section  shown  on  I'lule  II., 

l'ig.4.  ,     , 

Tension.  —  \  stress  tending  to  elongate  a  body. 

ThreaJ.  —  The  spiral  part  of  a  screw  or  nut. 

Through  Bridge.  — A  bridge  with  overhead  bracing. 

Tie.  — .\  tension  iniMnber;  generally  refers  to  a  main  truss. 

Timber  Truck.  —  A  small,  strong  wooden  frame,  with  an  iron  roller  set 
entirely  below  the  upper  surface.  It  is  used  in  bridge  erection  for  moviiii; 
large  timbers  and  heavy  weigiits  along  a  runway. 

Tongs. —  Part  of  a  riveting  outfit;  used  for  holding  and  carrying  heated 

rivets. 

Transverse  Component.  —  \  component  in  a  transverse  direction ;  geiiLi- 
ally  intended  for  a  component  peri)endicular  to  the  jtlanes  of  the  trusses. 

Truss.  —  \\\  assemblage  of  tension  and  co.npression  members  so  arranged 
as  to  transmit  loads  from  intermediate  i)oints  to  the  ends. 

Trussing. —  A  poor  substitute  for  lacing  or  latticing.     (I'late  11.,  Tig.  S, 

r-iate  VI.) 

Turn  Buckle. —  .Similar  to  a  sleeve  nut,  and  for  the  same  purpose.  The 
siilesare  open,  so  that  a  crowbar  maybe  inserted  for  the  purpose  of  screwiin; 
tip.  Turn  buckles  are  used  for  larger  bars  or  rods  than  are  sleeve  nuts. 
(I'late  II.,  Fig.  1 6.) 

Ultimate  Strength.  —  The  greatest  load    ;hat  a  [Hirtion  of   material   can 

bear. 

Uniform  Load.  —  .V  load  so  distributed  over  an  entire  structure,  that  eiiual 
lengths  everywhere  receive  ecpial  portions. 

U-nut.  — A  piece  of  iron,  in  the  shape  of  the  letter  U,  through  whidi  passes 
the  threaded  end  of  a  rod,  and  which  affords  a  bearing  for  the  nut,  with  room 
to  screw  up  the  latter.  Its  use  is  not  permissible  in  tirst-cla.ss  bridge  con- 
struction. 

Upper  Falsework. —  The  falsework  that  lies  above  the  level  of  the  l.nver 

diords. 

Upset  End.  —  An  end  of  a  rod  or  bar  enlarged  for  the  cutting  thereon  of 

a  screw-thread. 

Vibration  Rod.  —  A  tension  member  for  vertical  or  i)ortal  sway  bracing. 

(I'late  1.) 

Washer.  —  A  piece  of  cast  or  wrought  iron  to  distribute  the  ])ressure  of  a 

I  ol;  head  or  nut  over  tiiiiluT.     '  I'lato  il..  Fig.  6.) 


li  hiivf  to  1)C'  aderwanls 


;s  that  aiicct  the  dcsigii- 


tion  shown  on  Plate  11., 


GLOSSAh'\-    OF    TKAWfs. 


243 


Web.  —  The  portion  of  a  truss  or  beam  I)etwcen  the  flanges.     Its  office  is 
piiiiripally  to  resist  shear. 
Welded  Heads.  -  Heads  first  worked  into  shape,  then  welded  on  the  l>ars 
Whipple  Truss.  — .See  Linviile  truss. 
Wind  Shakes.  — Cracks  in  timber  caused  by  the  wind  while  the  tre 


e  was 


Working-Drawings. -iJrawings  containing  all  the  measurements  neces- 
sary lor  construction. 

Working-Stress.  -  The  stress,  usually  the  greatest  stress,  to  which  a  i.iece 
1.1  nial.rial  is  or  should  be  subjected.  Sometimes  incorrectly  employed  for 
iiiliiisiiy  of  working-stress. 

Wrench.  — A  tool  for  screwing  up  nuts. 


ling  and  carryiug  healed 


HHij 


1 

•'aBBBt 

i 

■i    ■ 
i 

.i 

INDEX. 


•Sa 


111 


<i 


INDEX. 


Allowance  for  waste,  68,  183,  190. 

Anchorage,  8,  104,  148. 

Aiifilf  irons,  19,  146. 

Area  opposed  to  wind  pressure,  6,  4S. 

Jiars,  best  proportions  for,  79,  80,  89. 

Hatter  braces,  limiting  slope  for.  7. 

Hattcr-brace  plates,  minimum  dimensions 
of,  14. 

Pattfr  braces,  proportioning  of,  6j,  132. 

Hattcr-bracc  sections,  1 1,  63. 

Heam-liangcr  plates,  ij,  loi,  146. 

•'(.•am  lian.ners,  23,  75. 

licains,  wooden,  23,  67  ;  Tables  xiii.,  xiv. 

Bearings,  21,  77,  93;  Tables  xxvi.-xxviii., 
xxxvi.,  xxxvii. 

Bearing-stress,  13,  76, 

lit'd  plates,  16,  104,  146. 

lieiuling  effect  of  wind  on  posts  and  bat- 
ter braces,  9,  52. 

BciuliMg-strcsses,  intensities  of,  13,  78. 

Iit;nts,  199,  200,  203. 

Best  iiroportions  for  bars,  79,  80,  89. 
Hi'Vfis,  iSi. 

Hills  of  iron,  yi,  113,  114,  rsi,  152. 

ol  lumber,  115,  155. 

of  rivets,  151,  190,  192, 

of  bolts,  188,  191,  205. 
Bills,  erecting,  204,  205. 

order,  183,  185. 

shipping,  19a 
Bolts,  23,  24. 
Bond,  168. 

Bottom  chords,  59,62,66,  215. 
Braces,  side,  7,  164. 

latter,  7,  9,  14,  6j,  133. 


Brackets,  22,  53,  103, 148. 

Uridge  lettings,  157. 
Bridges,  classification  of,  5. 

styles  of,  7,  38. 
liuilt  Hoor  beams,  12, 19,  68,  107;  Tables 
xix.-xxi. 


Camlier,  9,  175,  176. 
Camber  blocks,  200. 
Carpenters'  tools,  198. 
Cast-iron,  24. 
Cast-iron  portals,  58. 
Channel  bottom  chords,  11,  66. 
Channels,  properties  of.  Table  xxviii. 
Checking,  method  of,  ri6,  iSr,  182,  198. 
Chord  bars,  59,  62,  66,  79. 
Chord  heads,  20,  177. 
Chord  l)acking,  62,  81,  132,  179,  206. 
Chord  jjlatcs,  14,  63, 
t'hord  projiortioning,  64,  129,  130. 
Chord  sections,  i  r.  59,  62,  63,  66. 
Classification  of  bridges,  5. 
Clear  headway,  7. 
Clear  roadway,  6. 
Closed  columns,  56. 
Columns,  formula  for,  12. 
Complete  dcsinn  for  a  bridge,  126. 
Comprossive  stresses,  12. 
Connecting-plates,  15,94-99,  137-144. 
Connection  for  lateral  systems,  10, 98-100. 
Continuous  spans,  9. 
Contract,  form  of,  167. 
Cost,  estimates  of,  116. 
Cost  of  bidding-expenses,  170. 
of  blacksmithing,  170. 
of  eiecticni,  iiy. 
247 


i! 


248 


INDEX. 


Cost  of  falsewDvk,  117. 

of  franung,  1 17. 

of  hauling,  117. 

of  Uimljcr,  68. 

of  painting,  117. 

of  jiilc-drivcr,  198. 
Counters,  12,  40,  41.  46,  59-  61,  127.  132- 
Countersunk  rivets,  91. 
Cover  plates,  16,  95,  144' 
Cutting  off  flanges  of  channels,  23,  59,96. 

Data,  table  or  list  of,  3S,  1 18. 

Dead  load,  6,  32,  126,  156. 

Deck  bridges,  46. 

Demonstration  of  floor-beam  formula,  219. 

Depths  of  truss,  economic,  3S,  124;  Ta- 
bles iv,  V. 

Design  for  a  bridge,  126. 

Details,  jiroportioning  of,  75,  86,  93,  136. 

Diagonals,  length  of,  177,  221. 

Diagrams  of  stresses,  40,  127  ;  Tlate  v. 

Diameters  of  rivets,  15,  90;  Tables  .\.\i.\., 
xxxvi.,  xxxvii. 

Dimensions,  marking  of,  iSo,  iSi. 

Distributi(Mi  of  material  in  struts,  59. 

Double-intersection  bridges,  7,  44. 

Draughtsman's  equipment,  172. 

Draughtsmen,  hints  to,  180. 

Drawings,  working,  172, 

Economic  depths,  38,  124. 

Economy,  57,  59,  120. 

Effect  of  wind  pressure  on  members,  9, 

48,99,  215. 
End    lower  lateral-strut  connection,  104. 
144. 

I'.nd  lower  lateral  struts,  10,  56,  65,  135. 

I'.nd  panels,  stilfen-.l,  11,62,  66.  129,  215. 
Eipiipment,  draught.unan'.i,  172. 
for  raising  gang,  197. 

i:,|nivalent  length  for  iU-'ada, nuts, etc.,  115. 

lueeting-bills,  204,  205. 

I'',recting-gang,  196. 

Erection,  196. 

Estimates  of  cost,  1 16. 

Iv\pansion,  S. 

l'"..v])ansion  joint,  103,  104. 

l-lxpansion  rollers,  21,  103,  t4l,  20S. 

l':xtension  i)hites,  16,  96,  145. 


19,  68,  107  ;  Tables 


Eyes,  20,  105. 

ICye-bar  heads,  20,  177,  178. 
Falsework,  198. 

Falsework  pillars,  sizes  of,  Table  xxxix. 
Felly  plank,  23,  67. 
Field  riveting,  24,  92,  125. 
Filling-plates,  145. 
Fillers,  104. 
Final  order  bill,  185. 
Flanges,  19,  68,  107. 
Floor  beams,  built,  i: 
xix.-xxi. 
details  for,  19,  30,  71,  no. 
limiting  depth  for,  19. 
riveted  to  posts,  lOl. 
rolled,  12,  71. 
trussed,  30,  72,  109. 
Flooring,  23,  210,  211. 
Floor  system,  67. 
Foremen,  197,  204. 
Form  of  bond,  168. 
of  contract,  167. 
of  projiosal,  166. 
of  specifications,  162. 
Formula  for  built  beams,  19,  219 
for  coUinms,  12. 
fcjr  trussed  beams,  72. 
Framing  falsework,  117,  Z03. 
Friction,  riveted  plates,  90. 

shoe,  8,  II. 
Functions  of  J-beams,  55,  56. 

Cas-jiipe  i-lruls,  36. 
Cieneral  specilkations,  5. 
Girders,  18,  19,  71. 
Cuard  rails,  23,24.  • 


Hammers  pile-driver,  198. 

Hand  railing,  23,  24,  67. 

Hangers,  I)eain,  12,  22,  75. 

Heads  of  eye  bars,  20,  177,  17S. 

Headway,  7. 

Hints  to  draughtsmen,  180. 

Hip  connection,  .'•;3,  95,  137,  138. 

Hip  verticals,   12,  14.  59-  6'  !  Tables  vi.- 

viii. 
Hub  pUuik.  23.67,115. 

I-beams,  13,  55.  56,71. 


L\/)i:x. 


249 


S,   20,   177,   178. 

liars,  sizes  of,  Table  xxxix. 

23.  C". 

(,  24,  92,  125. 

,  145' 

)ill,  185. 
58.  107. 

built,  12,  19,  68,  107  ;  Tables 
xi. 

ar,  19,  30,  71,  HO. 
depth  for,  19. 
;o  posts,  lOI. 

2,7'- 

30. 72,  109. 

,  210,   211. 
1,  67. 
17,  204. 
id,   168. 

act,  167. 

nsal,  166. 

ficatidiis,  162. 

■  Imilt  lieams,  19,  219 

nuns,  12. 

sed  beams,  72. 

scwork,  117,  203. 

■etcd  plates,  90. 

I  II- 

if  I-beanis,  55,  56. 


pile-(lii\er,  198. 
ig,  23,  24,  67. 
earn,  12,  22,  75. 
yc  b.irs,  20,  177,  i~?>- 

1  ■ 
aiiulUsmen,  iSo. 

L-tion,  .S3,  95,  137.  '3^- 

lis,   12,  14.  59.  6'i  'I'al'l"  ^i'- 

,  2;,.  fl7.l'5• 
3,  55.  jC'.  71. 


Im  linatioiis  of  lattice  and  lacing  bars,  15, 
Iiulirect  transferrence  of  stress  by  rivets, 

92. 
Inilial  tension,  10;  'I'able  i.\. 
lii^lni'tion,  21 1. 
liitL-nsily  of  bearing-stress,  13,  76. 

of  bending-stress,  13,  78. 

of  compressive  stress,  12. 

of  tensile  stress,  11,  [2. 
Iiilermediatc  strut  connection,  98,  144. 
Iiitinnediate  struts,  51,  56,65;  Table  x.xv. 
imn,  bills  (jf,  71,  113,  114,  151,  152. 

cast,  24. 

hand  railing,  23,  24. 

weight  of,  33,  155,  156. 

Jaws,  22,  100,  104,  106,  143,  144,  149. 
JiMiu,  sliding  expansion,  103,  104. 
Joints,  top  chord,  94,  139,  179,  20S. 
Joists,  2^,  67,  209;  Tables  xv.-x^•iii. 

KiKcs,  or  knee  braces,  22,  53,  103,  148. 

I  ,iliiir  in  erecting,  117. 

in  framnig,  1 17,  19S. 
[,.uing-bars,  15,  [02,  146,  iSi  ;  Table  xxxi. 
i.aleral-rod  connection,  10,  99,  106. 
Lateral  rods,  14,  4S,  6r  ;  Table  xxv. 

strut  connection,  98,  104,  144,  [45. 

struts, 9-1 1, 49,  56,  '.',65,  135;  Table 
xxv. 

svstems,  48,  61. 
l.atlire  bars,  15,  102,  146;  Table  xxx. 
I.tngths,  limiting,  6,  7. 

of  diagonals,  177,  221. 

of  lattice  r.nd  lacing  bars,  102  ;  Table 
xxix. 

ol  span,  6,  7. 
lAtlini;  bridges,  157. 
Limiting  depths  of  pony  trusses,  7,  123. 

depths  of  lloor  beams,  19. 

lengths  of  span,  6,  7. 

sizes  of  sections,  8,  57. 

slope  of  batter  braces,  7. 
Limit  of  clear  roadway,  6. 
Li-t  of  data,  38,  118. 

of  mend)ers,  28. 
LiM'  loads,  5,  Ti^i,  37,  126. 
Ltiads,  deatl,  6,  ^2,  126,  156. 


Toads,  live.  5.  32,  t,7,  126. 

snow,  35,  46. 

for  wooden  beams.  67  ;  Tables  xiii., 
xiv. 
Lock  luits,  22. 
Loop  eves,  20. 

Lower  end  of  post  rc-cnforcing,  95,  142. 
Lumber,  amount  per  panel,  Tables  xv.- 
xviii. 

bill  of,  115,  155. 

list  of  members,  28. 

iNLain  diagonals,  59,  177,  221. 

members,  55,  (x). 
Maintenance  of  bridges,  211. 
Marking  iron,  system  of,  192. 

of  dimensions,  180,  iSi. 
Material  in  struts,  distribution  of,  59,  64. 
Materials,  bill  of,  71,   113,   114,   115,  151, 
'52,  155. 

tests  of,  25,  26. 
Measurements,  method  of  recording,  180, 

181. 
Mend)ers,  list  of,  28. 
Method  of  erecting  a  bridge,  196. 

of  (inding  lengths  of  diagonals,  176, 

of  reccjrcling  measurements,  180,  181. 
Nfcthods  of  checking,  116,  181,  182,  198. 
Middle  of  |)ost  connection,  96. 
Minimum  dimensions  of  chord  and  batter- 
brace  plates,  14. 

Xanic  i)lates,  24. 

Xeglccteil     consideration     in     highway- 

britlgc  designing,  215. 
Xumbc"   of   men   recpiired   for    erecting 

bridges,  1 17, 
Nuts,  22,  115. 

( )ak  lumber,  weight  of,  6. 

use  of  tables  with,  61,  75. 
Order  bill,  tinal,  185. 

prelimin.irv,  183. 
( )rnamental  work.  141). 
Outfit  for  draughtsman,  172. 

for  erecting-gang,  197. 

Lacking,  chord,  62,  81,  132,  179,  206. 


250 


INDEX. 


i'  |i 


T';iiiitin!T,  25,  117,  209,  211. 

raiifl  lengtli,  most  economic,  38,  123,  12S. 

of  toj)  chord,  exact,  176. 
rilc-drivcr,  19S. 
Pilot  mits,  84. 
Tin  bearing.  21,  77.93- 
I'iiie  lumlier,  6,  23,  24. 
Pin  holes,  21. 
I'in  pilots,  84. 

Pins,  proportioning  of,  76,  85. 
steel,  Si,  83. 

working  bcnding-moments,  etc.,  for, 
Table  xii. 
Plant,  197. 

Plate  girders,  7,  19,  71. 
Pony  trusses,  7,  123. 
Portal-strut  connection,  99,  143. 
Portal  struts,  52,  54,  61,  65 ;  Tabic  xxv. 
Posts,  9,  40,  41,  43,  45'  46-  59.  64.  133' 
Posts,  hand  rail,  23,  67. 
Post  sections,  II,  58. 

Practical  method  of  pin  projjortioning,  85. 
Pieliniinary  order  bill,  183. 
Proportioning  of  batter  braces,  63,  132. 

of  beam-hanger  plates,  loi. 

of  beam  hangers,  75. 

of  bottom  chords,  62,  66,  128. 

of  brackets,  103,  14'^- 

of  built  floor  beams,  68. 

of  chord  bars,  62,  66,  1 28. 

of  counters,  60,  127,  130. 

of  details,  75,  86,  93,  136. 

of  end  lower  lateral  struts,  65,  135. 

of  expan.sinn  rollers,  103,  141. 

of  falsework,  19S. 

of  floor  system,  67. 

of  hip  connection,  95,  135. 

of  intermediate  strut  counection,  98, 
144. 

of  intermediate  stmts,  65. 

of  joists,  67, 

of  knee  braces  or  knees,  103,  148. 

of  lateral  rods,  14,  61. 

of   lateral-s'.ut   connection,  99,    103, 

143.  145- 
of  lateral  struts,  61,  65. 
of  lateral  systems,  60. 
of  lower  end  of  posts,  96,  142. 
of  lower  lateral  struts,  65,  135. 


Proportioning  of  main  truss  members,  60. 
of  middle  of  post  connection,  96. 
of  pins,  76,  85. 

of  portal-strut  connection,  99,  143. 
of  portal  struts,  61,  65. 
of  posts,  64,  133. 
of  re-enforcing  plates,  93,  96. 
of  rivets,  91. 
of  rolled  beams,  71. 
of  rollers,   103,  141;   Tables  xxxiv., 

XXXV. 

of  shoes,  97,  140. 

of  side  bracing,  7. 

of  sway  br.icing,  61. 

of  top-ch<ird  coimection,  94,  129. 

of  top  chords,  63,  1 28. 

of  trussed  beams,  109. 

of  upper  end  of  post  connection,  95, 

MS- 
of  upper  lateral-strut  connection,  gS, 

143- 

of  upper  lateral  struts,  61. 

of  vd)ration-rod  connection,  98,  105. 

of  vibration  rods,  61. 
Proportions  for  bars,  best,  79,  80,  89. 
Proposal,  form  of,  166. 

(Quality  of  workmanship,  25,  166. 

Ratio  of  width  to  depth  of  bars,  79,  88. 
Recording  of  measurements,  180-182. 
Reduction  of  ends  of  pins,  84. 
Re  enforcing  plates,  16,  93,  96,  142. 
Rivet  heads,  90,  150;  Table  xxix. 
Riveting,  field,  24,  92,  125. 

rules  for,  17,  90. 
Rivets,  bending-moments,  etc.,  for.  Tables 
xxxvi.,  xxxvii. 

bill  of,  151,  11/3,  192. 

countersunk,  91. 

diameters  of,  15,  90. 

in  llanges  of  beams,  20,  107. 
Rivet  spacing,  18,  20,  107,  181. 
Roadway,  clear,  6. 
ki)d>,  eipiivalent  lengths  for  upper  ends, 

etc.,  1 1 5. 
Roller  plates,  16,  104,  146. 
Hollers,  21,  103,  141. 
I  Rules  for  riveting,  17,  90. 


INDEX. 


25' 


f  main  truss  members,  60. 

f  post  connection,  g6. 

85. 

rut  connection,  99,  143. 

ruts,  61,  65. 

^  133- 

ing  plates,  93,  96. 

I. 

;anis,  71. 

103,  141 ;   Tables  xxxiv., 

7,  140. 

cing,  7. 

icing,  61. 

d  connection,  94,  129. 

(Is,  63,  1 28. 

beams,  109. 

ml  of  i)ost  connection,  95, 

ucral-strut  connection,  98, 

iteral  struts,  61. 
n-ro(l  connection,  98,  105. 
n  rods,  61. 

r  bars,  best,  79,  So,  89. 
of,  166. 

kmanship,  25,  166. 

to  depth  of  bars,  79,  88. 
neasurements,  180-1S2. 
nds  of  pins,  84. 
lates,  16,  93,  96,  342. 
D,  1 50 ;  Table  xxix. 

24,92,  125. 
17,90. 

^■moments,  etc.,  for.  Tables 
cxxvii. 
I,  !</),  192. 
nk,  91. 
of,  1 5,  90. 
of  lieams,  20,  107. 

18,  20,  107,  181. 
r,  6. 
■nt  lengths  for  upper  ends, 

5- 

1(1,   104,    146. 
,3,    141. 

ting,  17,  90. 


Scales,  172,  204. 

Sections,  limiting  sizes  of,  8. 

Sections  of  members,  8,  11. 

Shearing-stress,  -^-j,  80,  91. 

Shipping-bill,  190. 

Shoe  connection,  97,  140. 

plates,  16,  97,  140,  146. 
Side  bracing,  7. 

sj/c.-.  of  floor  beams,  Tables  xix.-xxi. 
of  hip  verticals,  Tables  vi.-viii. 
of  joists.  Tables  xv.-xviii. 
of  lacing-bars,  Table  xxxi. 
of  lateral  rods.  Table  xxv. 
<if  lateral  struts.  Table  xxv. 
of  lattice  bars.  Table  xxx. 
of  pillars  for  falsework.  Table  xxxix. 
or  pins.  Si,  86,  134. 
of  portal  rods,  Table  xxv. 
of  portal  struts.  Table  xxv. 
of  rollers,  Tables  xxxiv.,  xxxv. 
of  sections,  limiting,  8,  57. 
of  stay  plates.  Tables  .xxxii.,  .\,\,\iii, 
of  vibration  rods.  Table  xxv. 
Skclctiui  diagram,  40,  44. 
Skew  bridges,  3,  75. 
Sleeve  nuts,  i  r^. 
Sliding  expansion  joint,  103,  104. 

of  pedestal,  8. 
Snow  load,  35,  46. 
Spacing,  rivet,  18,  20,  107,  l8l. 
Specitications,  5,  1G2. 
general,  5. 
on  tile,  162. 
Spikes  23,  151,  210. 
Splice  |)lates,  15,94,  139. 
Star  iron,  58. 

Mav  plates,  137;  Tables  .xxxii.,  xxxiii. 
Sleel  pins,  81,  83. 

Suffeiied  bottom  chords,  11,62,66,  129, 
-•15. 
hip  verticals,  14. 
Milfeners,  ic),  70. 

Stresses  on  batter  braces,  9,  41,  45,  52,  54, 
12S. 
on  beam  hangers,  75. 
oil  bottom  chords,  41,  43,  45,  128,  215. 
on  brackets,  53. 
on  built  beams,  107. 
on  chords,  41,  43,  45,  12S,  215. 


Stresses  on  counters,  40,  45,  127. 

on  double-intersection  trusses,  44. 

on  end  lower  lateral  struts,  10,  54, 135. 

on  falsework,  200. 

on  floor  beams,  73,  107. 

on  hip  verticals,  41. 

on  intermediate  struts,  51. 

on  lateral  systems,  48. 

on  lower  lateral  rods,  49. 

on  lower  lateral  struts,  49. 

on  main  diagonals,  40,  45,  125. 

on  pins,  76. 

on  portal  rods,  51. 

on  portal  struts,  51,  53. 

on  single-intersection  trusses,  38. 

on  sway  bracing,  61. 

on  top  chords,  41,  43,  44,  128. 

on  trussed  beams,  109. 

on  trusses,  3S. 

on  upi)er  lateral  rods,  49, 

on  ujjper  lateral  struts,  49. 

on  upper  lateral  systems,  48. 

on  vibration  rods,  51. 
Structure,  test  of,  26. 
Styles  of  bridges,  7. 
Sway-bracing,  9,  48,  61. 
System  of  marking  iron,  192. 

Table  of  data,  38,  118. 

Tee-iron,  19,  58. 

Tensile  stresses,  intensities  of,  11,  la. 

Tension,  initial,  10;  Table  ix. 

Test  of  structure,  26. 

Tests  of  materials,  25. 

Thicknesses  of  webs  of  channels,  Table 

xxviii. 
Threads,  14. 
Timber,  23,  25. 
Tools  used  in  erection,  197. 
Tojvchord  connection,  94,  129. 

joints  in,  94,  139,  179,  208. 

panel  length  of,  176. 
Top  chords,  41,  43,  44,  63,  128. 
Truss,  economic  dejjth  of,  38,  124. 
Trussed  beams,  30,  72,  109. 
Trusses,  pony,  7,  123. 
Trussing,  14,  103,  148. 
Turn  buckles,  22,  115. 
Turning-in  of  channel  llangos,  58. 


I 


252 


LXDKX. 


Units,  2. 

Upper  end   of   post   connection,    i6,   95, 

faiscwoik,  104. 
lateral  rods,  14,  49,  61. 
lateral-strut  connection,  9S,  143. 
lateral  stmts,  9,  11,  49,  61,  65. 
Upset  rods,  14,  115,  165. 

Vertical  sway  bracing,  49,  61. 
Vibration  rods,  51,  Ci. 

Washers,  22,  1 1;2. 

Waste,  allowance  for,  68,  1S3,  190. 

Web  stiffening;,  t9,  70. 

thickness  of.  Tabic  xxviii. 
Weights  of  materials,  6,  6S. 

of  iron,  total,  in  bridges,  35,  155,  156; 
Tables  i.-iii.  I 

of  rivet  hcatls,  151.  156;  Table  x.xix.   ! 


Widths   of  flanges    of    channels,   Table 

xxviii. 
Wind  pressure,  amount  of,  6. 
area  opposed  to,  6.  48. 
effects  of,  9,  ^S,  99,  215. 
Wooden  hand  railing,  23. 

lateral  struts,  10,  100,  [49. 
Working  bearing-stresses,  intensities  of, 
'3-  76. 
bending-stresses,  intensities  of,  13,76. 
compressive  stresses,   intensities  nf 

12;  Tables  x.,  xi. 
drawings,  172. 

loads  for  wooden  beams.  Tables  .\iii., 
xiv. 

shearing-stresses,  intensities  of,  76. 

tensile  .stresses,  intensities  of,  u. 
Workmanship,  25. 

Wrought-iron,  weights  of,  33,  71,  [31,  i ;;,-, 
156;  Tables  i.-iii. 


INDEX  TO   ADDENDA. 


f!cam-hangcr  plates,  226. 

Fioor-beam  connection  to   foot  of   post, 

228. 
Floor-oeam  stiffeners,  22S. 
Foot  of  post  connection  to  floor  beam,  228. 
Improved  beam-hanger  plates,  226. 


Improved  portal  .strut  connection,  229. 
upper  lateral  strut  connection,  228. 
Lateral  strut  connection,  228. 
Portal  strut  connection,  229. 
Proportioning  of  beam-hanger  plates,  226. 
Stiffeners  for  iloor  beams,  228. 


40 
50 
_6oJ 
70 
80' 
90 
100 
no 

120 

130 
140 

160 
170 

180 
190 
200 
210 

22cF~j 

230 

_240 

2503! 
'260  __j 

270_| 

280    Ij 

290_J 

300     1 1 


f    channels,   Table 


nt  of,  6. 

6,  48. 

9,  215- 

23- 

100,  r.|9. 

sscs,  intensities  of. 

ntensitics  of, 

'3.76. 

ses,  intensities  of, 

i\. 

)eanis,  'ral)le> 

.xiii.. 

intcnsities  of, 

76. 

tensities  of,  i 

of.  33.  71.  '3' 

' '  5:> 

A. 


■onncction,  229. 
coiniection,  23,S. 
1,  228. 
229. 

langcr  plates,  22IJ. 
IS,  22S. 


TABLE   I 

OT    OF    IRi 

CLASS  A, 


18'  Roadway 


6pan„ 


rERAi.  J  Floor 
STEM,  1  System. 


40 

20 

50 

20 

60 

"lO 

70 

-  S7 

80 

-■;< 

90 

-4Q 

.49 

no 

-  55 

120 

■5'  . 

130 

-  57 

140 

'5°Z 

-  61 

160 
170 
i8o~ 
190 

200 

210 

220 

230 

240 

250 

260 

270 

280 
290 
300 


77 

S4 
86 
86 
80 
^7 

89 


/i 


fl 


TABLE   I. 

TABLE    OF    WEIGHTS    PER    LINEAL    FOOT    OF    IROr 

GLASS  A. 


Span.  1 

i 
iKl^^aliS. 

1- 

:    '43 

12 

Lateral 
System. 

Roadway. 

1 

14 

Roadway. 

16' 

Roadway. 

18 

Roadway. 

Klckik 
System. 

Limber. 

193 
194 

1S7 

'93 
200 
219 

230 
24. 

D.  L. 

400     j 

404 

423 

469   ' 

-ST3-I 

Trusses. 

I,ati;kal 
System. 

1  LOOK 

Svste.m. 

LlMUKR. 

I).  L.     . 

,  'I'mssES. 

Latkrai. 

SVSTKM. 

Floor 
System. 

Ll'MUEK. 

,D.  L. 

Trusses. 

'53 
192 
184 

'99 

-'4  „ 

'» -» 1 
-,)- 

279 

Lateral 
System. 

20 

20 

FiJJOR 

System. 

Lumber. 

40 

26 
'   30 

!      '45 

20 
20 

39 
41 

-  '  / 
21S 

210 
"217 

407       j 

'47 

20 
20 
30 

54 
47 

48 

54 

_  74 

54 

242 
244 

443 

4S8 

500 
526 
541 

575 
636 

266 

50 

16S 

!54 
161 

-or 
2:0 

20 
.50 

'75 

442     ! 

i      182 

68 

268 

60 

44 

164 

170" 

30 
52 

57 

459_ 

473 
486 

'      '74 

1^1 8rr^ 

200 

221 

242 
266 

233 
::42 

30 

57 

53__ 

4') 

5S_  _ 

51  _ 

-_54  _ 

86 

257 

70 

49 
45 
43 

30 

44 

69 
65 

266 
276 
291 

"" 

?0 

::S 

1S2 
221 

48 
45 
45 
50 
46 

53 
49 
53 
6f. 

40 
40 

225 
241 
2(>9 

25« 

50      1      250 

50          !         26(') 

47       1      308 

' 

90 

29 

522 
5S2  " 

64 

' 

100 

43 

30 

39 
41 

39  "■ 

47 

61 

336 
3'4 
336 
3'4 

no 

42 

33 
32 

518   '. 

240 

2fxS 

298 

i       320 

|_354 
370 

53 
48 

54 

50 

286 
308 
285 
308 

692 

"714 

754 

779 

f'3 

120 

44 

55'     ' 

2(^) 

_25,S__ 
269 

269 

2|;S 

6.5 
644 

295 
330 

48 
51 

3'7 
l346_ 

~'374~ 

62 
64 

130 

52 
49 

35 

230 

57S     i 
602 

42 
41 

140 

34 

241 

672 
703 

745     ' 

1     354 

!   390^ 
i   389 

4'3 

426 

461 

491^ 
489 

49 

50 

Al^ 

i36 

150 

— . — 

44 

55. 
■    69 
74 
7" 
80 

Ji     _ 

286 

77  7 

-s 

""79"* 

Sr 
Hi 
83 

83  ' 

84  _ 
Sli 
>S() 

<p 

89 

1 

66 

3'4 
336 

160 



43^ 

5' 

55 
53 
55 
53 
55 
54 
55 

-3S8— 
2S6 
308 

811 

'822 
Z857: 

87C> 
.^.922    i 

90,5 

_  04(' 
962 
1012 

'053 
1077 

-__399_ 

440 

_470  ^ 
_509_ 
S07_ 

549 
'    587 

621 

661 

603 

739 

780 

"826" 

872 

1 

64 

170       ' 

! 

;-_374___ 
395 
424 

74 

45 
43 

67 

3'4 

180 

--    — 





t 

72 
75 

26() 

773     1 

64 
O9 

336 
3'4 

190 

— 

1 

45 

25S       796   i 

286 
308 
286 

r  308 

286 

200 

:                   i 

7" 
79 
76 

79 

78 
Si 

67 
7' 
68 

72 

."^ 

73 

1    72__ 

71 

^  ■» 

/  - 

7' 

336 

3'4 

_336_ 

3'4 

210 

- 

!i                          1 

220 

n         1 

1 

514 

548 
57S 

230 

, !                 1 

240 

—  -    -    ■■ 

— 

54       i      .'^OvS 

5;             3°8 

"54            308 

336 

3P 

3.36 

250 

,__j 



— 

641 

260 



i 

1 

80 

2-0 





280 

336 
336 
336 

290 

i 

i                    j 

300 

i 

TABLE   I. 

:.    FOOT    OF    IRON    PRATT    TRUSS    HIGHWAY -BRIDGES. 

CLASS  A. 


18 

Roadway. 

20 

Roadw 

ay. 

LlMnER. 

D.  L. 

22 

Roadway. 

24 

Roadway. 

Span. 

<l)SSES. 

SVSIKM. 

20 
20 
30 

57 
^}_ 

4')  * 
49_ 

55* 

St 

57 
=  -54_ 

61 

77" 

-s 

79  I 
St 

Si 

~'^3" 
«3  " 
«5 

S(p 
'     SC- 
SI) 

90 
S9 

Fl.Of)R 

System. 
68 

Lumber. 

D.  L. 

482 

535 

545 

Trusses. 

Lateral 
System. 

20 

Floor 
System. 

Trusses. 

_'59__ 
300 
202 
203 
216 

Lateral 
System. 

1 

Floor 
System. 

Lumber. 

1 

D.  L. 

:      559 
616 

Trusses. 

168 
20^ 

Lateral 
System. 

Floor 
System. 

■      87'"" 
105 

1 
Lumber. 

D.  L. 

153 

266 

2f)8 

-57 

161 
201 

207 

72 

290  _ 

292 

528 
582 

21 

23 

— 

30 
63" 

S9 

79 

315 

2 1 

■_339 
.  34' 

327 

600 
'  664 

40 
50 
60 
70 
80 
go 

192 

21 

81 

90             317 

22 

I'''4_ 

86 

30 

100 

82 

78  ^ 

74 

2S0 

290 
_30'~ 

325 

628 

646 

-"683 

743 

116             304 

640 

..2'S 
210 

223 

30 
67 
63 

'.36 

696 

.■w_ 

6y 
65 

266 
276 

580 

598 
626 
686 

60 

92 
"89 

3'S 

663 

.^'05     L_339  ^ 
113      1       -!';2 

____7'o_  : 

739    1 

7S4 

214 

221 

S'3 
5' 

327 

681 

23-^ 

64 
61 

291 
336^ 

243 

242 
274 

S3 
52 

56"' 

86 

86 

"  89 

88 

35' 

733 

253 
293 

33<^ 
374 
436 

55 

110 

107 

■"376  "" 

249 

267 

SO 

S3 
60 

.S9_ 

71 
74 

__364 

34-^ 

364    " 
__342__ 

404 
382 

807 

834 

53 
60 

58 
66 

,._.432 

410 

S-6    , 
911     : 

966   ; 
1009 

100 

279 

63 

3'4 

__336__ 
3'4 
^13'''    ' 

70.1 

75« 

300 

-335  __ 
372 
„  J97 

764 
S06    i 
841 

:  8S4 " 

3^3 

"3 
no 

no 
j    120 
i    130 

140 

_-'5o__ 
160 

3'7 

62 

72 

350 

391 
388 

404 
..382 

890 

432 

3t«J_ 

64 

773 
8r4 

_75 

63 

9' 

919 

IIS     i     410 

.)'J9 

6X 
66" 

72 

__364__ 
342 

62 
69^ 

90 

90      '     404 
93      1      382 

93(> 

966 

"^''035 

436 

64 

7' 

"4          4.32 

___"7 410 

116     1     432 

1028 
1067 

374 

3'4 
336 

80S 
"860 

40c 

41S 

457 
482  ~ 

66 

75 

876 

933 
957 

—429  __ 
457 

476 

399__ 

64 

85 
88 

87 

73           3f'4 

9> 
95 

404 

502 

^_  ^96  _ 
99 
98 

11.39 

422 

67 
64 
69 

3'4 

^_«7.-»_ 
912 

77 

74 

342     ■ 

497 
,     524 

^.  93.  _ 
92 
95 
93 
96 

._95_. 
98 
96 

99 
.98 

lOI 

100 

!  /°3^  _ 
101 

382 

1060 
1108 
1132 
1189 

546 

120 
119 

410 

116S 

170 
180 
190 
200 
210 
220 
230 
240 
250 
260 

440 

336 
3"4 

364     i 

1000 

95  ;     404 
-_^?8  _,__382 

96  ,     404 

576 
621 
662  " 
662 
696 

'752' 
802 

_    859, 

.904 

959 

1002 

1062 

nil 

432 

I3l8 

470 

927 

5'9 

90 

79      :     342     1 
77       ;      3f'4      ■ 

1023 
1076 

io6i 
I  "3 

5'''4 

101 

-9? 
102 

lOI 

r  .'04 ._ 

103 

'03 

106 

^los"" 

'07 
106 

122     i     410 

(247 

5o<) 

67 
7' 
68 

72 

7.1 
0() 

_72 

71 

^  ■> 

/  - 

7' 

_  336 

3'4 
_336_ 

3"4 

336 

3.3'' 

,53<^ 

336 

986 
968 
1029 
1051 
1 103 
"1149 
1177 
1230 

554 
555 
589 

"73 

7>S 

75- 

798 

84.  _ 

892 

93'' 

88 
91 

603 

-605   _ 

644 

12! 

7_  432  __ 
410 

'307 
1 291 

',345 
1384 

507 

So 

342 

_364 

342 

97 
"  96 

382 

124 

549 

90 
93 

94 
93 
96 

95 
98 
96 

_     77     _ 

404 

1232 

'23 

432 

5'^7 

So_ 

ii4« 
1190^ 
1250 
1282 
"1335^ 
'.375 
•4.32 
•472 

,  6S9 

733 

782 

821 

874" 

919 

._973__ 
1020 

loi           382 

1263 

'324 
1380 

1417 
__'478 
1520 
1580 
1623 

125 
124 
139 
_I26 
'30 
129 

'32 

'3' 

_4'°^ 
432 
432 

02  I 

78           3C4 
81       1     364     , 
So            3f'4 
83      :      3''4 

_.98__._ 
102      ^ 

404 

'453 
i5'8 
1558 

66  f 

404 

Cm 

loi      1     404 

l-'°5    J '.404  ^^ 
103           404 
106           404 

.._4.32  __ 
432 

739 

1621 

270 
280 

7  So 

336 

336" 

336 

1268 
1318 
1362 

Si 

"84"' 

82 

3^-4 
3''4 
3''4   ' 

432 

4.12 

432 

1663 

,S26 

1727 

290 

,S72 

104 

404 

'774 

300 

-1 
-4 

11. 

F    IRON    ] 

S  B. 

r' 

— 

Jway. 

P_                 . 

SF 

.M. 

Ll'MllBK. 

I),  t 

266 

47v 

1 

ilkS 

SK^ 

~257'^' 

5  lie 

266 

55': 

.  =76__ 

56*. 

2<)l 

S'lk,'- 

1 

33<' 

"5; 

1 

3'4 

66', 

1 

_'336_.. 

7'.'. 

1 

3'4 

7^'( 

I 

336_^. 

7()»< 

3'4. 

78r 

_   336„ 

81; 

3'4 

82„ 

_336_ 

86; 

3'4 

J_87 

3,V' 

9" 

3M 

9a 

336_ 

94 

3'4 

(/. 

- 

}i<> 

100) 

33'- 

1     104! 

1      3;" 

10- 

!     ^;" 

T  1  1 

1,  ',<> 

1  I.) 

'      1  iS 

.;>' 

u: 

E    II. 


F    IRON    ] 


S  B. 


r' 

iway. 



24' 

Roadway. 

Sf 

Span. 

1 

1 

, 

<K 
M, 



! 

Ll!MIIEK. 

l>.  I  1.. 

Tri.'sses. 

I.ATHRAI. 
SVSTKM. 

^^:i^.  '— ■ 

1).  1.. 

j 

266 

2(>S 

257 
266 
276 

2()I 

•»7i33 
5i;S9 

S«io4 

'43 

'   184 

1S4 

'79 

1   '94. 

,      226 

21 

78 

339  ^ 
341 

567 

•  129  1 
(152 

7C0^ 
746 

_  40 

!  50 

1  70 
1  80 
'  90 

22 

94 

30 
67 
62 

122 

3=7_. 
..3.W 
352 
376 

SS'23 
5fH44 

5')l.S7  ! 

_  94.. 

lOI 

98  ■" 

>> 

-  — 

33(> 
3'4 

3.16 

0570 
66:9, 
7  "41 

200 
297 
327 

53 
60 

58 

96 
101 

43.2 
410 

^A3^ 

861 
()09 

100 

no 

i  120 

9<) 

432 

-'  — 

3'4 
330 

3U 
336 
314 

33*' 

7-'<)5 

i   3"S 

64 

71 

103   1   410 
105   1   410 

<)40 
988 

r  -,,89 

1  ""10.S7' 
1078 
1 122 
1144 

U_'30 

;   140 

:  .50  j 
160 
170 
180 

i  190 
200 

76te^ 
78^0 
8 1 '162 

82,S2 
SO:25~ 

1«7:43 
9  "03 

397 

409 

43' 

4(>S 

492 

t— S3?__ 

:    563 

96 

99 

'■98 

104 
107 
106 

.432 
410 

I.432_ 
410 

1   432 

101 

I0<) 

-  — 

3M 
3' 4 

_9?!77 
_  94,28 

•/"SI 

564 
596 
641 

102 

lOI 

104 

III 

410 

!  ii8i 

'233 
1261 

210 
1 220 

:  230 

no 

432 

112  1  410 

33" 

100J05 

(>So 

102 

i  '" 

.  .  432 

1319 

240 

-'._ 

53<^ 
33" 

104*52 

10"  Sj 

1;  725 
701 

105 

'03 

i   "5 
1   "3 

43- 

1  ~  1 

1  10;, 

250 
260 

,V,<' 

1  .  1  ;, 

807 

10<) 

!  i.r,  !  4>' 

1 .1  V ' 

7ro 

2   '  ;,;(. 

"4.<)4 

842 

.OS 

i   IIS     13- 

'   I4^'l 

280 

'          ^\(> 

I   iiSiij 

i,  891 

'07 

iiS     t;,2 

IS43 

290 

3      vP 

122.48 

9-'' 

10<l 

iir    13- 

1  s'^o 

'   300   , 

1 

— 

TABLE   II. 

TABLE    OF    WEIGHTS    PER    LINEAL    FOOT    OF    IRON    I 


CLASS  B. 


40 

5" 

60 

;o 

80^ 

90 

;ao 

'.10 

:20 

:;o 

;40 

oO 

:6o 

:-o 

:So 

igo 

:90 

210 


230 

240 

2jO 
200 
2-0 

;!,-. 

250 
ICO 


197 

2l6 

48 
44 

49 

30 
29 

32 

239   ! 

2->2 

3' 

! 



.  1 
1 





: 

— 



TABLE   11. 

700T    OF    IRON    PRATT    TRUSS    HIGHWAY- BRIDGES. 

CLASS  B. 


IMAGE  EVALUATION 
TEST  TARGET  (MT-3) 


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Photographic 

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23  WEST  MAIN  STREET 

WEBSTER,  N.Y.  14580 

(716)  872-4503 


ABI 

OT    ( 

CLA 


18'  R(. 

Spai 

rKRAL 

Fi 

40 

>TEM. 

SVJL 

- 

20 

i" 

20 

•■ 

bo 



JO 

70 

r  80 

57 

' 

S< 

40 

♦y 

♦9 

120 

55      ' 

5' 

no 

57      ' 

140 

ISO 

54 

ibo 
J  70 

n 

7S 

190 

'9 

{I 

200 

U 

220 

<3 

2,0 

<3 

240 

^S 

250 
260 

'4 

^6 

^(t 

270 

280 

V 

2qo 

»7 

^00 

W 

J 

'9 

' . 

ABI 

OT    ( 

CLJ^ 


i8'  R(. 

Spai 

24'  Roadway. 

Span. 

rEKAL 
iTEM. 

40 
—^-20 

Kl      1 

SviUMBER.     D.  L. 

Trusses. 

Lateral 

SYSTE.M. 

Sl^^il        I^-B-- 

D.  L. 

315 

536 

139 

21 

71    339 

557 

40 

60 

■  70^° 
-80  57 

-90  5^ 
-,oo»9 

-..0*9 

301 

56s 

172 

22 

85 

„32S 
327 

594 

50 

304 

593 

172 

172 

30 

no 

629 

60 

_3'S 

623 

67 

86 

339 

656 

70 

327 
333 
357 

644 

■83 

62 

92 

351 

681 

80 

665 

210 

55 

89 
87" 

358 

705 

90 

711 

238 

272 

^300"^ 

53 

38s 

757 

1  100 

120  55 
-  .30^5. 

.40  57  - 

.50  5=* 
1    " 

100 

341 

357 

736 

60 

92 

366 

78s 
828 

no 

774 

58 

90 

385 

120 
130 

34 « 

801 

337 

66 

94 

366 

858 

-357 

832 
862 

3(>i 

._  64  __ 
7' 

93 

385 

899 

140 

341 

374 

96 

3(^ 

901 

150 

n 

357 

884 

392 

96 

94 

385 

961 

160 

-  'r  'If" 

341 

904 

425 

99 

97 

366 

9S2  1  170   II 

,90  ^-f- 

357 
.341 

933 

958 
998 
984 

442 

98 

96 

385 

1016 

180 
190 

i  200 
1  210 

220 

230 

'   240 

[    250 

1  260 

'   270 

280 

290 

30ft 

t 

481 

lOI 

99 
102 
101 
104 

99  i   366 

1042 

'2.0  ^i— 
220  ■^ — 

..  357 
34' 

5" 

98 

385 

1088 

508 

536 

577 

612 

"653-^ 

68s 

lOI 

366 

1072 

.357 

1023 
1050 
i094~ 

100 

385 

tii7 

240  J — 

"  2S0  "* 

34' 

•357 

(02 

366 

385 

1 144 

102 

101 
104 

1 195 

26^  ^6- 

J80  ^9 

"290  *7 

w  »^  - 
•9 

.357 
...  .,357 

^.'■38_ 
1162 

ios_ 
'03 

385 

1242 

102 

'O5 
104 

107 
106 

385 

1271 

,357 

,157 

.._;357 
357 

1207 
">235 

727 

106 

385 
385 
.385' 

385 

'3'9 
J.346 
1399 

758 
804 

105 
107 

1283 

.35. 

838 

106 

143' 

TABLE   111. 

TABLE    OF    WEIGHTS    PER    LINEAL    FOOT    OF    IRO^ 

CLASS  C. 


12  Roadway. 

14'  Roadway. 

16'  Roadway. 

18'  Roadway. 

Span. 

no,c<:,-c   Lateral 

iRlSSts.   SYSTEM. 

sLr,.  Lumber. 

D.  L. 

Trusses. 

Lateral 
System. 

i 

D.  L. 
410 

Trusses. 

Lateral 

System. 

Kloor 
System. 

LUMBHR. 

V.  L. 

Trusses. 
143 

Lateral 
System. 

20 

Floor 
System. 

49 

Lumber. 
266 

40      143       20 

-5 

'93 

368 

494  i 

143 

20   1   33 

217 

143 
161 

20 

40 

241 

431 

50      I'll       20 

29 

194 

161 

20 

35 

208 

414 

20 

45 

232 

448 

167 

20 

57 
72 

255 

5o     140     30      42 

187 

389     144 

30     47 

210 

421 

148 
•58 

30 

62 

45 

234 

464 

490 

'58 
167 

30 

57 

257 

70      I4.S      49 

So    149     45 

27 

193 

409     '53 

52 

37 

217 

451 

54 

241 
247 
249 

272 

58 
54 

266 
271 

24 

198 

409 

158 

48 

34     222 

455 

166 

50 

42 

498 

S'2 

545 

_^79_ 
194 
206 

53 

90     1J9     43     24 

198 

418 

170 
181 

45 

34 

223 

465 

181 

47 

42 

49 
49 

52 

274 

;oo     169     43      23 

217 

446 

45 

32 

245 

497 

'93 

47 

39 

49 

301 

no     180     48      26 

206 

455 

•97 

50 

34 

232 

S08 

213 

S3 

42 

257 

560 

23' 

55  '       52 

290 

120     198     44      25 

217 

479  1 

219 

46 

32 

245 

_53Z-__.. 
559 

239 

268 

48 

40 

272 

594 

256 

St     50 

_30'_ 
290 

130     JI9      52      28 

206 

500 

244 
260 

285 
298 

S3 

35 

232 

245 

__-32._ 

245 

54 

43 

_==57__ 
272 

257 
272 

617 

284 

57     53 

140    :-!,2           49     27 

217 

520 

49 

34 

S«3 

289 

49 

42 

647 

301 

54 

51 

301 
290 

-_J°' 

150 



53 
66 

36 

601 

3'6 

55 

45 

668 

327 

61 

54 

160 

35 

639 

11' 

69 

43 

710 

344 

77 

52 

ro 

3'8 

74 

37 

.,  232 

656 

33' 

74 

46 
44 

257 
272 

703 
729 

343 

78 

SS 

290 

ibo               1 

;      1 

3>8 

72 

75 

35 

245 

665 

342 

76 

35<'> 

79 

53 
56 

30 ' 
290 

:qc 

j 

340 

37 

232 

679 

370 

80 

46 

257 

748 

409 

81 
81 

200 

390 

386 

76 

44 

272 

767 
763 

54 

301 

210 

! 

79 
76 

46 

257 

405 
426 

83 
83 

57 

290 

220 
230 

1 

405 

45 

272 

793 
810 

55 

301 

1 

433 
456 

79 

46 

257 

457 
483 
5'5 

538 

85 
84 
86 
^  SO  " 
^) 
87 

58 

290 

240                       1 

1 

78 
81 

45 

272 

846  j 
878 
^  897 

56 

301 

250 

1 

484 

46 

272 
272 

59 

301 

260 

1 

505 

80 

45 

56 
59 

_30'_. 
301 

270         ' 
280 

1 

1 

!         1 

574 
603 
638 
668 



i 

1 
1 

1 

1 

1 



57 

301 

301 
301 

290 



90 

89 

59 
57 

300  < 

1 

1 

TABLE   111. 

.    FOOT    OF    IRON    PRATT    TRUSS    HIGHWAY -BRIDGES. 

CLASS  C. 


i8'  Roadway. 

20'  Roadway. 

22'  Roadway. 

24'  Roadway. 

Span. 

USSES. 

Lateral 
System. 

20 

Floor 
System. 

49 

Lumber. 
266 

D.  L. 
465 

Trusses. 

Lateral 
System. 

Floor 
System. 

Lumber. 

290 

D.  L. 

— . ,  1 

Floor 
System. 

Lumber.   D  L. 

Trusses. 

Lateral 
System. 

Floor 
System. 

Lumber. 

D.  L. 

'43 

146 

174 
168 

20 

60 

503 
530 

148 

21 

!   64 

315 

536 

139 

21 

71 

339 

557 

40 

ib7 

20 
30 

57 

255 

__4_89_ 

21 

67 

278 

178 
175 

22 

74 

301 

565 

.72 

22 

85 

325 

594 

50 
60 

iS« 

72 

257 

507 

30 

83 

280 

551 

30 

94 

304 

593 

'72 

172 

30 

110 

327 

629 

ib7 

57 

58 

266 

540 

172 

60 

68 

290 

582 

177 

63 

76 

315 

623 

67 

86 

339 

656 
681 

70 
80 

'79_„ 

53 

54 

271 

55° 
562 

599 
623 

•83 
204 

56 

64 

295 

591 

190 

59 

75   1  327 

644 

'83 

62 

92 

351 

!94_ 

49 

_  52 

274 

5' 

62     308 

618 

2T3 

2:^b 

S3 

73 

333 

665 

210 

55 

89 
87"" 

358 

70s 

1   90 

206 

49 

49 

301 

225 
254 

SO 

58     329 

656 

52 

70 

357 

711 

238 

272 

53 

385 

757 

100 

23' 

55   1   52 

290 

56 

61   1  3'6 

682 

269 

58 

73 

341 

736 

60 

92 

366 

785 
828 

no 

256 

5'     50 

301 

653 

277 

53 

59 

329 
3'6 

713 
738 

294 

56 

72 

357 

774 

300 

58 

90 

385 

120 
130 

2S4 

57     53 

290 

679 

305 

60 

62 

327 

63 

75 

341 

801 

337 

66 

94 

366 

858 

301 

54 

5' 

301 

290 

702 

322 

59 

59 

329 

764 

344 

62 

74 

357 

832 
862 

363 

64 

93 

_J85_ 

899 

140 
150 

327 

61 

54 

_„348_ 

66 

62 

_3l6 

_  7l7 

380, 

69 

77 

34J 

374 

71 

96 

366 

901 

344 

77 

52 

_JO' 

769 

337 
365  ' 
379 

85 

60 

329 

806 

367 

90 

75 

357 

884 

392 

96 

94 

385 

961 

160 

343 

78 

55 

290 

761 

88 

63 

3'6 

827 

397 

93 

92 

78   1  341 

904 

425 

99 

97 

366 

082  i 

170 

3S^> 

79 
81 

S3 
S6 

301 
290 

784 
808 

87 

61 

329 

851 

412 

77 

357 

933 

442 

98 

96 

.385 

ior6  ; 

180 

3SO 

411 

90 

04 

316 

876 

447 

95 

80 

341 

958 

481 

lOI 

99 

366 

1042 

I  go 

409 

81 

54 

301 

840 
"830 

436 

88 

62 

329 

910 

475 

93 

78 
81 

357 

998 

5" 

99 

98 

385 

1088 

200 

405 

83 
83 

57 

290 

432 

9' 

65 

3>6 

899 

47' 
496 

533 

96 

341 

984 

S08 

102 

lOI 

366 

1072 

210 

220 

230 

240 
250 
260 
270 

426 

55 

30' 

860 

455 

90 

62 

329 

931 

95 

80 

357 

1023 

536 

577 

lOI 

100 

385 

i"7 

457 

85 

58 

290 

885 

489 

93 

65 

3'6 

958 

9,8 
96 

83     34' 

1050 

104 

102 

366 

"44 

483 

84 
86 
86 

"  »<; 

87 

56 

301 

919 

553 

91 

63 
66 

329 
329 

996 
1037 

565 

81 

357 

1094 

612 

653 
68s 

t02 

lOI 

385 

"95 

5' 5 

59 

301 

956 
976 

94 

603 
630 
669 

99 

9^^ 

lOI 

84 
82 

_3S7_ 
357 

_"38_ 
1 162 

105 

'03 

104 

385 

1242 

53'^ 

56 
59 

30 « 
30  • 

577 

93 

64. 
67 

329 

1059 
1 100 

102 

105 

385 

1 27 1 

574 

1019 

612 

96 

329 

85 

357 

1207 
123s 

727    106  1 

385 

I3'9 

603 

57 

30' 

1044 

644     95   1 

05 
68 
66 

329 
329 

tI29 

1173" 

700 
742 

100 
«03 

lOI 

83 

357 

758    105 

104 

38s 
385 
385 

'346 

280 

638 

90 
89 

59 
57 

301 
30 ' 

1084 
(III 

682 

98 

86 

357 

1283 
•35' 

804 

107 

107 

'.399 

143'  1 

! 

2go 

668 

713 

96 

329    raoo  j 

774   j 

84 

357 

838 

106 

106 

30f> 

\ 


niBMIMIMIf 


TABLE   IV. 

ECONOMIC  DEPTHS  AND 
PANEL  LENGTHS. 


Span. 

So' 

yo'" 

100' 

No.  of 

Depth. 

Panels. 

SlNC.l.K 
NTBRSECTION. 

Dnimt.E 

NTEKSKCTION. 

5 
5 
S 
6 

16.  ?' 

18' 

- 

20' 

no' 

120' 

21' 

6 

21' 

26'      .^ 

'30' 
.40'" 

'50' 
i6o' 
.70' 
i8o' 
.90' 

200' 
210' 

7 

22' 

7 

23' 

8 

23' 

26' 

8 
9 

24' 

27' 
29' 

26' 

9 

27' 

30'          _ 
32' 

'     33' 
34' 

35' 

10 

!      10 

i      0 

220' 
-'30' 
"240' 
250' 
260' 
270' 
280' 
290' 

I      II 

' 12 

36'       ^ 

12 

38' 
^39' 

13 

'3 

40' 

14 
14 
'S      „ 

';     '5 

41' 
■         42' 

;    «'  -  -- 

44' 

1         . 

PI 


m 


£>i>.''%tiLE£££M» 


TABLE   V. 


ECONOMIC     DEPTHS    AND 
PANEL    LENGTHS. 


Span. 

.So' 

90' 

100' 

No.  of 
Panels. 

1 
Depth. 

SlMil.R 

Intkksh  niiN. 

If).!' 
IS' 

DoiiBl.E 

Intkkski  rioN. 

5 

5 
5 

20' 

no' 

120' 
1  ,?o' 
140'  ' 

5 

81' 

22' 

22' 

23' 
24' 
25' 

5 

6 

6 

26' 

'50' 
\(yo' 

i;o' 

i.so' 

190' 

200' 
2 1  o' 
220' 
2  ;o' 

2.(0' 
250' 
2(X)' 

7 

27' 

7 
S 

8 

2.S' 

27' 

30' 

2S' 

32' 

34' 
35' 
36' 

9 

10 

10     ~ 

37' 

P' 

10 

1 1 
1 1 

40' 

■ 

41' 

42' 

270' 

2.S0' 
2()0' 
JOO' 

13 

12 

'3 

13 

43' 

44' 

4.S' 

4(/ 

MHi 

'% 

''^^^S 

A 

■^B  c-  - 

n 

1 

9f ' 

II 

* 

m\ 

' 

-xlpl- 


-n 


TABLE   < 


In   which  tlic 

wDfkiii^-strcs 

The  uppc 

;i()iis  ri<iuii"C( 


Panel  '* 

Length.     RoaJ' 


IC 


0.01 


i.oo 


/ 

2  r' 

12 

1.09 

'--  li 

13' 

l.iS 

1 
/                  i 

2  \% 

14       ! 

1.27 

„ 

f 

2   4 

15 

\ 

i.3(. 

'      16' 

a  r 

\ 

1.45 

/ 

2  V 

«7 

'•54 

18' 

2ir 
..64 

;  2  ij' 

19' 

'■7.^ 

'21" 

20' 

i,S4 

21' 

-   '" 

I.V5 

2    lA 

2.07  I 


23' 


34' 


h'.1 


:  'I' 
2.29  I 


I 


\ 


TABI 


111  whic 

\\iiikii\i^ 

The 

;iiiii.s  tl'i 


Panel 


I 


>3' 
'4' 
'5' 
i5' 

17' 
18' 

'9' 


I      ^ 


23 


\» 


\ 


24 


TABLE    VI. 

TABLE   OF   SIZES   OF  HIP  VERTICALS    FOR    BRIDGES 

OF    CLASS  A, 

III   which   thi'  hvt,'  load   i>.  owe  liiiii(lr(.'(|   pdiiiuls  ]n-v  st\udiv  foot   of   tioor,  ami   the 
\\nrkiiij;-.strt'ss  on  the  verticals  is  lour  tmis  to  liu'  s(|iiarc  inch. 

'i'lic  ii|>|»i'r  fi,L,Mircs  i;ivi-  the  sizes  nf  the  hi|.  vi'ilicals ;  the  lower  ones,  the  sec- 
;  idiis  mniired. 


Panel  12'  I4'  16'  18'  2o' 

Length.    Roa  Iway.    Roadway.    Roadway.    Roadway.  ;  Roadway. 


ic 


•3' 
'4' 
■5' 
16' 

'7' 
18' 

'9' 


-•    I  "CI 

0..JI  a" 

2  fn 
1.00  □" 

J    i"G 

1.09  n" 

2  H"a 

I.lSu" 

2  ir'u 
1.27  a" 


22 

23' 
24' 


2  S'a 
1.36  a" 

2  ;"a 
1.43  a" 

2  iru 

1.04  a' 
2  \Va 

2  1"  □ 

r..S4  a' 
J    l"U      i 

-■  'yn 

2.0;  CJ"  J 

2  i.'.'a'^r 
2.i.sa"    I 

2.2()  n"    I 


2  fn 
i.ooa' 

"2  fro" 

l.lfjD" 

2  H!"ir 

1.26  D" 

2  fiT 
1.370" 

2  i"a 

1.48  D' 

2'-B''d 

i.SyO" 


^  irn 

I.2I   D* 

1.33  a'_ 
1.45  u" 


2  5"  □ 
i.3sa" 

2  !?□ 
1.64  a' 


2  rn 

1.51  n* 


2  H"  □ 

1.69  a' 

2  i"D 

i.SoD" 

2  i"a 

1.91  a" 

2  r'a 

2.02  D' 

2  ii^B'a 

2.14  D' 

■nra 

«.sf»  a" 

2  n"a 

i.fxSd" 

2  I'D 

i.Si  D» 

2   I'D 

j-gin' 

2  ^ya 
2.0s  a" 

2.r7  a" 

2  .  r  D^ 
2.29  D" 

77i"a" 
2.43  D' 


2  ir'D 

1.77  a'' 

2  I" a 

1.90  a* 

2  ■,>-," n 

2.04  D" 

2  lya 

2.18  a" 

2  iji"a 

2.32  D" 

•  3  \ra 

1.66  0' 

2  i"q 

1.S1  D' 

2  I"  a 

1.95  D"^ 

"2' I, "5"  a 
2.10 :!" 


—— -n 

22' 

24' 

Panel 

Roadway. 

Roadway. 

Length 

2  ir'D 

1.67  D' 

2  i"a 
1.S4  a" 

10' 

2    I'D 

2  I'D 

U' 

1.84  D' 

2.03  n" 

2  r'a 
2.00  a' 

2   ■,',''0 

2.19  a" 

12' 

2  ii»»"n 

2.16  D" 

2  li'a 

2.36  D" 

13' 

2  li'a 
2.32  D" 


2  ii"o    ^ 
2-53  D"     • 


2  ii"a 
2.27  d" 

7  .l"a 

2.40  D" 

2  il'a 
2-53  □"_! 

2  ift'a  ! 
2.6.S  a'    I 


2  -A" a 

2.-,SD" 

-•  '.Va^ 
2.73  n" 


2  ri"n 
2.S7  □" 

I7i"  a"" 
3.01  n" 


:  'i"a 
I  ,i6  a" 


2  iiV'o 
2.(>i  a' 

2.760" 


2  i}"a 
2.92  n" 

•   2  i^"a 
3.00  a" 

2   lA'D 
3.27  D" 

2  1  ■■'. "  n 

2.71  c" 

2  ii"a 

2.s6a" 

2  lY'D 

3■°^  0" 

2  iA"a 
3.45  □" 


2  .ft' a 
"2  .ft ''"a" 

3-3"  n" 
2  .J"  7^ 

2  iT'n 
3-74  o" 


2  iV'a  I 

2.99  P"  ; 
2  «ft"a 

3-1'' O"  I 

2   .ft"D  1" 

3.34  □'  I 

3' 54  CJ"  i 

"'2  If  a  I 

3v4  G"  ' 

2 irt"a  ' 

3.95  □"  J 

2  T^"a"''' 
4.16  a" 


3'27  D" 


2  .t\,"a 
3-4('0" 


2  .r'a 

2  <i',"a 
3.87  a" 

7irt"n 
409  a" 


2  il"u    ! 
4.3; o"    I     =3 


«7' 
18' 

19' 
20' 

21' 
22' 


2  li'a 
4.56  n" 


24' 


TAB 


In  \vh 

uiukir 


Ih 


I  Kills  r 


Panel 
Length 


!        II 


13 

14' 
■5' 
16' 

17' 


i       'f 


■9 


12' 


23' 


TAB 


In    wli 

\\(M  kir 
Th 

h  Ills  r 


Panel 
l.uiiKth 


I 


12 


!       '3 

I         - 
;        14' 

'5' 
16' 

!     '^' 
J     -s' 

'9' 


^3 


J       '1 


TABL 


lii   whict 

uMi  kino-.; 

The  1 
tiiMis  rccj- 


!      Panel 
Length. 


10' 


I 


!       «i' 

12' 

I      13' 
>4' 


■^       1 
.6'      I 

■7' 
1 8' 

19' 


22' 


■!3 


-4 


TABLE    VII. 

TABLE   OF   SIZES   OF  HIP  VERTICALS    FOR   BRIDGES 

OF   CLASS   B, 

In   which  tlio  live  Io;ul  is  one  huiuhcd  pnuiuls  per  sciuare  foot   of  floor,  and  the 
udikin^-stress  on   the  verticals   is   ti\e  tons  to  the  stjuare  inch. 

The   upper  figures  ;4ive  the  sizes  of  the  hip  verticals ;  the  lower  ones,  the  sec- 
'  n'lis  recpiired. 


Panel  12' 

Leng 


'4 


i6' 


10 


!       II 


I  12 


^3 


'h.    Roadway.    Roadway.    Roadway. 


I8'  2o'  22'  I  24'  I     Panel 

Roadway.    Roa.lway.    Roadway.  '  Roadway.  I  Length. 


2  r  a 
0.72  a" 


2  i"a 
0.79  a" 


2  f''a 
0.86  a" 

7  i"  a" 
0.94  a" 

2  fa 
1. 01  a" 

2  fa 
i.os  n" 

2  \f,"a 
t.isa" 

2  ir  □ 

1.30  a" 

-  5' a" 

I.^SC" 

Ti'~a~ 


2  f  n 

2  f  n 

0.84  a' 

0.96  a" 

2  fa 

-'  fa 

o.(;2  a" 

1.06  a" 

2  fa 

-^  f,V'n 

1.00  n" 

r.isn" 

i.os  a"    ' 

'2H''"a~\ 
1.17  a"    i 

::  H"o    • 

1.260"      ! 

1.35  a" 


-  \ro 

1.24  a" 


2  i"a 
1.34  a" 

7";"  a 
■-t-1  g" 


I     r.09n" 

'■  -  ircTT 

1.20  D"       I 

I    '-.i'  g"    : 

1.41  g" 

2  l"a 
i-s-g" 

■:  W'a 
t.02  n"    , 


2  5"  a 
i.43_g" 

2  I'a 
I.S2  a" 


..61a"   1 

1.71  a"     :    r 

I     I. 


■'g 

.•>•>  g" 

2  {>"a 

-  i.V'g 
1.74  g" 


2  i"a 
1.830" 


2  I "  a 
I. Si  a" 

:  i"a 
1.91  g" 

2  I" a 

2.01  D" 

7  ..'.rg" 

2.11  a' 


2  j''a 
1.54  g" 

1. 04  a" 

1.7  ya" 

2  \"a 
I. S3  a" 

2  I" a 
r.94  g" 

-  i,'.i"D 
2.00  D" 

-  'rV'g 

2.1S  a" 
2.29  a" 


2  H'-a    \ 
r.7jg"    I 

2  I" a 
'    ''Ssg"    ! 
I    2  i"o 

S  1.9CD"  ' 

2.07  D" 

I  2  i^,,"n  ■ 
j    2.ic)n" 

I    2  ii"o 

r  -  <rc!  ' 

I    2.4C  n" 

I  2  t^"a  i 
I   2.60  n"    ; 


I.. -2  0" 

-  r^' 

2  ("  a 
1.44  aj'_ 

-    I.;     - 

'•.=i5g" 
Ijrg" 

1.67  a" 

:  i"D 
i.SoD" 

2  i"a 
1.93  a" 

:.05  D" 

3.17  g" 

^  ■r'g^" 

.:.J9g" 

:  il"g 

:.12  n"_ 

-  iu"g 
-'•57  g" 


2  V'a 
^•34_g^' 

2  rg 
'•47  g" 


2  n"a 

'•59  a" 

2  l-r'  a 

1.72  g" 

2  I'a 

..85  a" 

2  i"  a 

1.98  a" 

2  i^'a 

2.12  D" 

2   r,',,"a 

2.26  a" 

2  .i"g 

2.39  □" 

2  i\"a 

2.53  a" 

2  r'g 

'•45  □" 

2  [fa 
i.()o  a" 

'•74  a" 


2  i"a 
1.S8  a 


10' 


II' 


12' 


2  ra 
2.02  a" 


2   'I'r/'g 

2.16  a" 


2  ij"n 
2.31  a" 

rrfa 

2.46  a" 


»     ,      '3 

14' 

15' 

16' 

'7' 


2  'I's'g 

2.61  a" 


18' 


2  ii»,"a 
2.67  a" 

2  If  a 
2.83  a" 


2  !,'.."a 

2  If  a 

3.00  D" 

2  -i'  n 

j.sr,  n" 

2    'I'/D 

3-'7n' 

-  'fa    Lj 
2.76  a" 

2  i|"n 
2.<)2  n " 

2  if  a 
3.01)0" 

2  i^f  a 


19 


3  2S  0" 

2  'A'g 

147  D" 

'a 


-'.41  n" 


2  'I'/g 

2.-4  n" 


2  «l"a 


?3  C 


2  iT'g 

3.65  o" 


22' 

23' 
24' 


I 


\' 


lo' 

II' 
12' 

13' 
14' 

'5' 

16' 

'7' 
iS' 

as' 

22' 

23' 
24' 


ffc-^i 


TABLE   C 


In  which  the  I 
"tress  on   the 
riic   upper 
tiiiiis  reciuired. 


Panel 

12' 

Length. 

Roadw 

lo' 

2  f'l 
0.60  Z 

II' 

2  :l"i 
o.()5  C 

12' 

2  f, 
C.71  C 

13' 

,  ,i 

::  •}"[ 

14 

'5' 
16' 

>?' 
18' 

■9' 


o.S;,  C 

2  I"  I 
0.S9  C 


2  I"  I 


-  I    I 
I     I  01  c 

-r'i 

1.0;  c 

-  1 

1  .  1  ;,  C 

-■  U" 


i.-'>.  C 


23 

24' 


-    4" 
i-ll  C 


I.;; 


I 


SMMii*^ 


im 


r 


Panel 
Length. 

i 

1        10' 

:     ii' 

i 

1 

■        12' 

'3' 
>4 
'5' 
i6' 

1 

18' 

'9 

20' 
2!' 

- 

^Itf^^ 


.*.-« 


TABLE   VIII. 

TABLE   OF  SIZES   OF  HIP  VERTICALS   FOR   BRIDGES 

OF   CLASS    C, 

III  uhk-h  tlu'  live  loail  is  cii;hty  pDunds  per  square  foot  of  floor,  and  the  workinj;- 
-ircss  on   the  verticals  is  five  tons  to  the  sciuaic  inch. 

The  upper  figures  give  the  sizes  of  the  hip  witieals ;  the  lower  ones,  the  sec- 
tions retiuired. 


Panel 


Length.  [  Roadway. 


10' 


'4 
Roadway. 


'3 


'4' 
'5' 


,,r\  2ro 

o.<)5  n" 


2  f  n 
o.fx3  n" 

2  r  a 

0.6s  D" 

2  fa 
0.690" 

0.7  s  D" 

2  }"n 
C.71  0' 

2  i"  a 
0.S2  n» 

2  J"  a 
c.77  □" 

2  fa 
0.S9  n" 

2  |"n 
0.S3  n" 

2  f  n 
0.S9  n* 

2  }"n 

0.97  D" 

2  }"n 
1.04  n" 

2  fn  " 
0.98  a" 

2  f  □ 

20 
Roadway. 

2  f  n 

1  .CO  G " 

2  I'D  "" 

1.10  a" 


22'  24'  Panel 

Roadway.    Roadway.  |  Length. 


2  fn 
1. 12  n" 


'7' 


18' 


19 


23 
24' 


2  f  a 

MI  n" 


.11  n 


13"  □ 

.19  D" 


-  I"  a     i 
i-oi  n"    j 

1.07  n"    i 

2  fa     ' 
1.13  D"    I 


-  ira 

1. 2 1  n" 

2  fr'D    : 
1.2S  n"    i 

—r, 1 

-  4    n      : 
r.;,6n"     i 

2  i"  □ 
'•44  a"^  j 

-  Vn 


-^  ira 

1. 18  D" 

2  H'a 

1.25  a" 

2  IT  a 

1.32  D" 

-^  V'a 

1. 41  a" 

'^ 

U 

"n 

1 

J7 

□" 

2 

i 

•a 

1 

35 

a" 

2  I"  a 

r-jon" 

r.jS  a" 

-  ir"~a' 
1.67  n" 


2  r'a 

1.4,5  a" 

2  i"  a  ^ 
1-5'  a" 

2  1  .i "  n 

-  \ro 

1. 7 1  □" 

2  1"  n 
1. 8 1  n" 

2    !"□ 

1.90  n' 

2  i"n 
2.00  n" 


1.07  D" 

=^lra~[ 

1. 16  a" 

"2H"a'^: 
__>;=s_a"_; 

"2  fa    \ 
'•34  g"    j 

2  fa    ^"' 

1.42  D" 


2  U"a 

j     1.22  D" 

2  \r  a 
^■j3  a" 

2  i"n 
1.43  a" 

2  i.rn 

1.20  ;" 

2  ii'a 
1.3,  Q' 

2  j'T 
1.403" 

2  j'a 
1.50  a" 

i.io  Z" 


10' 


13' 


2  r'a     ! 
1.54a"     ! 

r^r'^a 

1.65  a" 


1. 51  a"    t 


2  H'a 
1.70  a" 


-  Kra 
I    1.(0  a" 

I  ^fr a 

I    1.70  a" 

[       2    I  "  lJ 

j    I  .yo  o " 
\2  i"'n 

I     1. 91  D" 


2  i"a 
2.02  a" 


2    13 

1..S1  3" 

2  ra 

1.02  a" 

2  i,vF 

2.03  y 

^  'A' a 
2.ir,a" 

2.2S  3" 


3fr'a 
1.76  a" 

2  i"n 
1.87  a" 

2  i"a 
1.99  a" 

2  'h"a 
2.11  a" 

16' 


2  iiV/'a 
-_--3p" 

'2  7j"a" 
2.36  a" 

2.50  a"    j 


19' 


ar 


aa' 


2  'A"  a  i 

2.13  a"  _ 

-   'i's"'J 
2.24  n" 


2  IJ'D 

2..10  a" 
"2  iyp7 

2.~:  -J" 


2.64  D" 

T^h"a~ 
2.rs  G" 


If  ^-M, 


II 

12' 

«3' 
14' 

'5' 
16' 

11' 
18' 

19' 
20' 


23 


Sl»— w™. 


TABLE   C 


In  whicli  the 
stress  on  the 
The  upper 
tioiis  re(|uire(l. 


Panel 

12' 

Length. 

Roadw 

2  f  1 

10' 

0.60  C 

II' 

2  i"i 

0.65  C 

12' 

2  r'l 

0.71  c 

13' 

2ri 

t.77!: 

,^' 

2  ft 

«5' 
16' 

»7' 
18' 

19' 
20' 


23 
21' 


o.S;,  C 
'  2    f~| 

0.S9  c 

"  2  r'l 

0.05  c 

-•  I"  I 

I  01  C 

3    f  1 

1.07  c 

■.    Iff  t 
-    (    ' 

1  .  1  ;,  c 

i.-M  r 
-  I.i" 

i.jS  z 

2  l"\ 

-  v' 

i-tt  c 


t 


1   .4^ 


■>-^*tf?%;^;.,<*''Mj&?-- 


I 


10' 


II' 


'3 


14 


'5 


U- 


17 


18' 


19 


20 


23' 


h 


^"'-^^^MiV^iUj/^^ 


TABLE   VIll. 

TABLE   OF   SIZES   OF  HIP  VERTICALS    FOR    BRIDGES 

OF   CLASS    C, 

111  wliii-li  the  live  load  is  eighty  pounds  per  square  foot  of  floor,  and  the  workinj;- 
>tress  on   the  verlieals  is  the  tons  to  the  si|u:irr  null. 

The  u\)\)vv  tijiurcs  give  the  sizes  of  the  hip  \iitieals;  the  lower  ones,  the  sec- 
tions reiiuired. 


Panel 

la' 

Length. 

Roadway. 

10' 

2  f  D 
0.6o  D" 

II' 

2  fn 
0.65  n" 

12' 

2  f  □ 

C.71  D" 

'3' 

2  fa 

<-77  □" 

14'       I       16' 

Roadway.    Roadway. 


«5' 
16' 

«7' 
1 8' 

19' 
20' 


2  fa 
:    0.S3  a" 

'    2  f "ni^ 
0.S9  n" 

2  fa 
0.1)5  a" 

2  r'a 
r  01  a" 


-     _ .    

2  fa 

2  fa 

o/k)  a" 

0.79  n" 

2  fa 

2  f  n 

0.7s  a" 

0.S7  n" 

2  :t"  a 

2  fa 

0.S2  a" 

o.<>5  a" 

2  fa 

2  fa 

0.89  D" 

i.oj  a* 

2  ^"0 

2  fa 

0.97  n" 

...in" 

2  fa 

2  ir'n 

1.04  a" 

1.19  a" 

2  fa 

1.07  a" 

2  }*"□ 

1.16  a' 

2  H"n 

1.25  a" 

23' 
21' 


2  fa 
1.07  a" 

.      1  »  r-i 
-      I       ■'^ 

1.1;,  a" 

2  vrn 

I.-' I  n" 

-  \Va 
i.jS  n" 

2  r'n 
I. Via" 

-  i"n 
i..t.t  a" 


2  fa 
I. II  a" 

1.18  a" 

7]ra" 

1^25  D" 

1.32  a" 

2  fa 
1.41  □'' 

"2  r  □ 

1.50  n" 


2  U"a 
1.27  a" 

T  2'"j"a^ 
'    1.35  a" 


1.43  a" 

•l"o 
r.si  n" 

-  ir'n 
i.(.i  n" 


.71  a' 


'n 


I-;; 


2  !?,"□ 

1.5'^a" 

2  ira 

i.f)7  a" 

a  ir'a 

1.7 ^  n" 

2  i"n 

I. Si  a" 

2  I'a 
up  a* 

2  I" a 
J. 00  n" 


2  jf  a 
1.70  a 

2  r'n 
i..^'o  n" 

-•  r'a 
i.yi  a" 


2  ra 
2.0;  a" 

2  1,^5"  a 

2.13  a" 


2  \i\-,"n 


2  irV.'n 

2  I  A"  a 

2.0.5  □" 

2.23  a" 

2  i,'«'a 

2  ira 

2.i()n" 

2.36  a" 

2  ii"a 

2  If  a 

2.2S  -" 

2.50  a" 

2  ifn 

2  I  h"  0 

2.40  G* 

2.64  a" 

2  if  a 

2  iA"n 

^    ~  ■,   ^f 

2.7S  r," 

2  if  a 
vo.^  n" 


....    .,.„*.-* v...i. 


In 

tlic 


In 

the 


! 


f 


it      a 


Ji, 


1 


TABI 


In   tons  of  two  ti- 
the initial  tension 


u 

Intensity  0 

OJ 

Stress  = 

E 

Q 

0 

r 

i.2r)S 

\r 

1.451 

i"   \ 

1 .650 

n"  i 

1..SS5 

i"    1 

J.140 

■i^" 

2.423 

"S" 

2.726 

'     1  i  " 

3.057 

-1" 

3.40S 

'  xV 

3-7S7 

4.190 

4.f.i7 

1 '," 
;   -k"  i 

5.o(xS 

5-547 

■  1.1"    : 

6.04(> 

6-573 

If      1 

7.120      ' 

ij-r  i 

7.fK)5 

,  1  i  '■    ' 

S.294 

'  iir'  ! 

«.9»7 

j"        ' 

9.568 

-'^" 

10.239 

A" 

'      1  o.(  );;S 

- 1  •' 

11.057 

1   H"     ^ 

1      12.404 

!    -'ft"    , 

i      '3-'7S 

--r' 

1     '3-')70 

,7    » 
-Vfi 

'  l-~'t,i 

A" 

1  vl>-," 

■■•"*«•#<.■ 


■  TABLE   IX. 

TABLE    OF    GREATEST    WORKING    STRESSES, 

]n  tons  of  two  thousand  (2,000)  pounds,  on  adjustal)le  round  and  square  rods,  exclusive  of 
the  initial  tensions  ;  also  the  initial  tensions. 


u 

e 

Q 
f 

7  " 

!i""" 

'A" 
■i" 
'  iV 
ti" 

1 1" 
'}.'."    1 

i|r'   ; 

If   1 

1;'     ' 

- 1  •> 

>  *  '' 
- 1.1 

-i"    '■ 
-h" 

-]'■•< 

-V 

Intensity  of  Working 
Stress  =  4  tons. 

1 

Intensity  of  Working 
Stress  =;  5  tons. 

Intensity  c 
Stress  - 

© 

)f  Working 
7.5  tons. 

1 

Initial  T 

ensions. 

u 

it 

1       1 
Q 

J" 

liV" ' 
"I" 

i   w 

;    1" 

I  ifV 
,''^"" 

■  i" 

i  ';v' " 
1  •-,  ■,» — 

;  'H' 

'f 

'iii'  , 
1  ij" "  1 

!  'H" 

i     2i" 
2^" 

I   2  A" 

!     2i"       ' 
2,\"        ' 

0 

u 

0 

01 

1.    m 
3-574 

4-'57 
4.789 

5-4:^i____ 

(1.230 

I     7-0.38' 
1     7.904 

r   8.830 
9-814 

10.850 

j    11-956 
1.3-117 

® 

—1 

I.26S 

~    '-45' 
1. 6  so 

2.140 

2-423  " 

i-5'7 

1.710 

2.178      ' 
2.507 

2.815 

.3_-76o 

4-303 

.|.S(K5 

6.205 

6:931 " 

0.500 
:       0.025"' 

0.63  s 
0.794 

0-953 

1.846 

1      1.970 
2-257 
2-576 
2.927 

3-308 

3620 
4.163 

2-875 

.3-284  __ 

3-730 

j       0.750 
!       0.875 
1        1.000 

2-405 
2-730 
3.0S7 

1.111 

1.270 

4.216 

1.125 

1.429 

2.726 

3-476 

4-740 

1.250 

1.588 
1.746 

3-057 

3-»94 

5-305 

1-375 
1.500 
1.625 

3.40S 

3-7«7 

4-347 

4-636 

5.140 
5-675 

5-908 
„iL'5S0__ 

7-2.10 

7-95' 
8.710 

7-704 

s-523  ~ 

9.3«7 
10.29S 

1.905 
2.064 

4.82S 

4.190 

5-341 

1.750 

2.22*1 

4f'i7 S-*^'^!^., 

5.o(kS             6.4(0 

1       6.240 

6.836 

1.875 
2.000 

2  381 
2.540 

"-253 

'4-335 

5-547 

7.065 

7-463 

9.508 

12.256 

15.611 

16.947 
,      18.342 

2.125 

2.699 

6.04(1 

7.706 

8. 119 

'0.345 

^„.i3^P4___ 

15-540 
16.726 

2.250 

2.858 
3.016 

6-573             8-.376 

8.8aS 

11.223 

2-375 

7.120 

9-077 

y.8io 

10.571 

9-527 
10.276 

12..38 

19-794 

2.500 
2-625 

3-3,i4 
3.493 

7-(m 

13-092 

21  .305 
22.874 

8.294 

8-9' 7 

'  9-5('''^ 

10.239 

11.056 

14.085 

17-959 

_i'>237 

20. 5(1  J 

23-3-1') 
24.811J 
2(1.321 

20.476  _ 

;j.Si  ; 

2.750 
3.000 

'i-36i__. 
12.190      1 

11.867 

1  vl  iS 

24.503 
2(1.190 

3.651 
3.810 

12.708 
13-580 
14..,83 

1      '5.4'7 
16.380 

'7-.?75 
18.400 

'9.457 

1CI.|I)0 

17.300 

18.450 

i<).f)40 

~  20867 

_22.23S___ 

23.440 
24.780    i 

-'ii.i;o 

13-047 

27.935 

29-7,39 

31.003 

'      3.3.524 

3-125 
3-250 
.3-.375 
3-500 

3-969 
4.128 

4.2S(, 

4445 

4.604  __ 

4-763_ 
4.921 

5.C80 

!      io.<)3S 

1 1  -657 

12.404 

'3-936 

14.854 
.5,807 

1      13.17s       i      I6.7S8 

1      35-504 

3625 

3-750 

__3:S75 
4.000 

1 3.()70 

1  v'.;(. 

17.801 

_j8rs4T:: 

37-541 

3<).(i40 

41  r'ls 

I 

4" 


1 


' 


L  t 

2 
2 

2 
2 

^ 


INIANNEL    STRUTS. 


Ratio, 

/,  to  D. 

IHii    S)® 

Ratio. 

A  K.  /'. 

64 

64i   " 
65 

66 

^■'.. 

10 

loi 

1   rr"~ 

1      ni 

4.20!   i.4t9 

4-I4!   1-377 
4.1  M   i-3S6 
4^oS:   1.335 

4-05,:   i-.VS 
4.02^    1.296 
3.99.;   1 .276_ 
3.96;   1.256 

3.901    1.219 
3.S7:   1.200 
3.841   1. 182' 
3.Sii   1.165 
_3-7'^'   '-M-S 

1.569 

'•553 

'•53« 
'•523 

12 

id 

'5 

■5i 
i6 

17 

1-508 

66.i 

67 
67.1 
68 
68i 

'■493 
1.479 
1.464 
1.450 
'•435 

6.ji 
70 

1.421 

:   '-407 

'■393 

70J 
71 

'•379 
1.366 

I7J        ! 

_,V75>   '•"30 

■'■"-' _L-1' -3  „ 
3(19;   1.097 

3.61  >;   i.aSi 

3-63:  J  .064 

3.60;   1.04S 

7..L. 

72 
'     7-^ 

73  ' 
1     73.' 
i     74 

'•353 

IS 

"'         i 

iM-i 

20 

1.340 

1     1-3-7 

i-3'4 

1.301 

!    I.2S8 

.-ol 

x"'    i-o.v'. 

:\': 

'•-"n 

::i 

21.1 

21\ 

,1-5 1.    i-oi.S 
y\\..   1.003 

3  |Si   o.<)SS 
;,.',;'  o.>);( 

I  75r 

"7C> 

7'V,      , 

1.2(13 

i"'-\si 

:    1.23S 

1.220 

j      -xi 

3.-IJ'    0..)()0 

7'^  J 

I.2r4 

1.202 

!      -M 

3.31K  0..)',  i 

7S 

i.itii 

-'■t' 

.l-viC    O.')J0 

-  ^  , 

1.171) 

^5 

3.311  o.i)07 
3.2S:  0..S94 
3.2^;   o.S.sf 

"'1 

s<-> 

1 . 1(  i.S 
1    1  V 
I.I  |(. 

27        1 

1  -  1 

5.2  2(    O.SuS 
319}    0.856^ 

3.r-(  o.S(.| 

S.i 

Si 

Si 

1.124^  1 
1 , 1 1  1 

tj  ®    i    ®  I 


1. 130 


I.!  16 
1. 102 

I  .aS8 
'•075_ 

1 .0(32 

'•049 
1.024 

I.OII 

O.IY)') 

o.(j87 

0-975 
0.96;, 
0.951 
0.939 

0.()2S 

0.1)17 

O.(i0li 

o  .S>)5 
Jo.SSs 

0.S7.1 
o.si).) 
0.S54 
o.S.14 

o.S-vt 
0S24 
o.S  1 4 
0.S05 
o.7')5 
0.780 

0.-77 
o.7(i.S 

<\"5>.) 
0.750 
0.741 


0.832 
0S20 


0.809 
0.797 
0.786 


_°-Z75. 
0.765 

0-754 

_^-Z44 

0-734 

0.724 

0-7 '4 
0.704 

0.f)<)| 

o.'iS5 

r.676^ 

0.067 

1.658 

0.649 

0.640 

0.032 

0,02  I 

0.01  (} 

0.60S 

0.600 

0.592  ■ 

0.5S4 

0-57*^ 
0.569 

0.5<i2 

0-555 
0.54S 

o.  5 )  I 

05.il 
0.527 
0.^20 


I 


^Ha 


,  '^■-J^:'~  '/»«»i«»**««i«***" 


INTENSITIE 


Ratio, 
A  to  D. 

Uti 

1     !%• 

O  d 

10 

1 

1 
4.205 

4- 140 

3.900 

i         10^ 

4±75 

4-103 

3-'M7 

~\\ 

i    4-145 

;     4.066 

3-')04 

Mi    ' 

4.IM 

i     4.029 

3.S(,2 

i::       1 

^__'»:°L^5 

'    3-993^ 

3„Sm 

I2i 

'    4-05;, 

i    3-95^' 

.5-775 

'.) 

i_i:°f3_^ 

1    3-9 '9 

3-73- 

'■3L..: 

3-993 

3.8S2 

3.aS,S 

i   '"* 

,Vr/'2 

,?S45 

3-<'45 

'-(i  ; 

,v93-  ' 

3-«07    1 

3.()0i 

'5       i 

3.901 

3-770 

,._3-557 

'5i    : 

3-.S72 

3-732 

3-5'4 

■        K) 

;vS4> 

3-<''')5    ' 

3-470 

I'.i 

;,.Sir 

._  3/'57    - 

3-4 -'4 

i        1- 

3-7.SI 

3.620    I 
_3-5'\3 

.1:^^^ 

3-75' 

.V34> 

1^ 

.vr-i 

3-54''> 

3--')5 

ISJ 

.•,.(.92 

_3.5aS    ' 

_3-252 

ly 

3.6()2 

J-471    ^ 

3.209 

'"J.  I 

3.632 

3-434 

3.1(1(1 

,      '°       1 

3.()Q2 

3-397 

_.v'-'3 

20)    J 

"3-573~" 

.3-360    1 

3.0.S0 

1 

.1-51? 

3-323 

3.03S 

2^\ 

,v^l  1 

3.2S6 

_  2.91)0 

'',      i 

_J4«5^J 

.3-250 

"j-9S3 

32i    ; 

3.456    ' 

.V2I4 

2.912 

1    -:?  .  1 

3-4-"' 

3- '78 

2..S7. 

-r?i 

,i-,)'): 

314- 

2.,S30 

:^4 

__  3-.i''9 

3. 1 G()      1 

_2.7.;o 

'  2-»rj 

3-340    i 

3.070       : 

2.750 

-^S 

3-i'i 

3■<^^^ 

2.710 

-5!. 

_3.^x^  ; 

2-<)')<) 

2.670 

,  ^6  j; 

J-- 54    ! 

2.964     1 

2.6  ;o 

:f,i      • 

V-'jd 

2.')2f) 

2.:^n\ 

J" 

3i,),s    . 

2.S.,5 

-■^i'l 

-Ti      ii 

3-f70 

^  2..S(iO 

.•515 

TABLE    X. 

INTENSITIES    OF    WORKING-STRESS    FOR    CHANNEL    STRUTS. 

CLASS   A. 


[0 

I  I 
11.^ 

12 


I  I 
ill 
I  > 

Id 
K.i 

IS 

|S) 

I') 

:i 

-' '  i 

2  "* 

22\' 


dd..« 

ii»3> 

#(§ 

1 

.(.JO  5 

.1.140 

,v90O 

■t-'7=; 

4.103 

J-947 

.(.i.i; 

.|.o66 

3-904    1 

,     .(.III 

.1.029 

3.862  1 

4.0S5 

3-'W.5 

;,.Si9 

Ratio.         ..-  — 

z  to  /;.  i  aa 


-(■o,s;, 
-♦-023 

3-993 

.V9.P 


C3® 

OdD 

1    Ratio, 
I  to  I). 

HIS 

2.826 

2-477 

46 

2.241 

2.792 

2.441 

47 
47i    ^ 

2.219 

-^759 

2.404 
2.368^ 

•■332 
2.297 

2.198 

2.725 

2.176 

2.692 
2.659 

48 
48.J 

2.15s 

2. '34 

2.627 

2.262 
2.227  ~ 

-A'93_ 
2.160 
2.127 
2.094 
2.061 

49 

2. 113 

-•595 

__19i_ 
5° 
sol 

2.092 

--53' 

2.072 
2.051 

2.500 

5' 

2.031 

2.46(j 
2.43S 

52 
52^ 

2.011 
1.991 

2.408 

2.030 

'-97 1 

-^378 

1.999 

53 

1.952 

2.34S 

1.968 

-1-S37Z 
1.908 

1.849 
1.820 

S3k 

••933 

2.318 

54 

1.914 

2.289 

S4i 

1.895 
..S76 

1.839 

2.260 

55 

2.203 

5Si 
56   ' 

-147 
J.I19 

'•793 

1.765 

•-73S 

S6i 

57. 
S7i 

1.8  21 
1.S03 

2.0()2 
-•.06; 
-'■039 

o'3 

1.0S7 

1.1X12 

M2 

I  ss- 

1.8(13 

8;u 

1,81; 


t.710 

1 .684 

17.58;' 

J -^31 
1.607 

'•5«3 
'-55« 

1S09 
1 .486 
1.46,1 

1-112 


5« 

i.7r)8 

_   SS-1 

59  _, 
"S9i 

60 

'-751 

'•734 
1.717 
1.700 

f)0i 

1.683 

6, 

1.666    1 

6..^ 

i.'>49  : 

62 

^'3 


I -"32 
1.616 
1.600 
1.584 


,1 


\ 


-s„ 


INTfiANNEL    STRUTS. 


Katio, 
/.  I.)  D. 

Gill 

10 

4-367 

'0^ 

4-343 

II 

4-3 '9 

^^\ 

4.294 

\z 

4.270 

I2i_ 

4.245 

'  .1 

.\.220 

\ 


INTENSITIES 


Ratio, 

/.  I.)  D. 

10 

IfiiO 

"* 

®© 

4-/'7 

4.299 

l-'43 

11 

4-343 
4-3 '9__ 

4.26S 

__4.ro5 

_  4-237^ 

4.067 

Hi 

4-94 

4.20f) 

4-029_ 

1 1 

4.270 

4-'75 

3-992 

.2i 

l4;245_ 

4.142 

3-950 

'3 

4.220 

4.1 10 

3-9 '4 

'.3i___ 

..'♦•.'91_ 

4.077 

3-875 

1 1 

l.Kx) 

l.045_ 

3-836 

Mi- 

4.144 

4.012 

3-795 

's       i 

4.1 18 

3979 

_  3-755_ 

15I 

4.o<).S 

.v<)4^> 

3-714 

i() 

4.o().S 

3-913 

3-674 

,r,,i_| 

4.042 

3-879 

__3A33 

''  __.' 

4.015 

3-S45 

3-5''-' 

'7) 

_.!•<)' K) 

.VSi, 

3-55' 

IS       1 

__3-0''t 

J-777    : 

3-j'o_ 

iSi      ' 

3-'»>'' 

^3-743 

3469 

!■) 

.)•')'-' 

3-70.S 

3.428 

n»J 

VSJSd 

,v''>74 

3'387_ 

JO 

3.,S(,o 

3-<'40 

3-346_ 

-'Oi 

3-\V> 

V(')o6 

3305 

Jl 

;v'So7 

3- =171 

3.J64 

-Mi 

3-7.SI 

3-537 

y--:^  ' 

ti 

3-755    ; 

.1-502 

3''82_ 

-V', 

3-7  ^S 

3-4f>S 

3- '42 

"  1 

3-702 

.)-433 

3.I02_| 

,  1  ' 

',,•17(1 

3-.VI.S 

;,.o()2   ( 

-'t 

,!■''!') 

3-VM 

3-o.:3  1 

-•■('. 

;.!._•;, 

.;■!-■') 

J..  ^3    1 

-■5 

.v3'i'> 

,v-'»5 

-"»3_i 

-•-.'. 

3-.vO    , 

;,.2;)i 

•■'m  '■ 

^(^■■"    II 

3-544    ! 

_3---7    i 

"2.864  ■' 

.hi_     : 

3-5'Sli 

3  I'M 

2.S2fi^ 

"' -  --  il 

.  3"»9i 

3.1(0 

2.7S8     1 

i7K.ii 

3-465 

3- '27^ 

2-750    ! 

TABLE    XL 

INTENSITIES    OF    WORKING-STRESS    FOR    CHANNEL    STRUTS. 

CLASSES   B   AND   C. 


iuC 

2.712 
2.674 

Katto, 
/,  to  Z>. 

■a      I 

1® 

®® 

i.6i6~ 

'-593 
1.570 

1.547 

'•525 

'•503 

r.4S2    ' 

..40,    I 

1.440 

1.420 

1.400 

r.3So1 

i.36o"'| 

'•342   i 

'■323 

'•305 

1.286 

1.268 

1.250 

.  '•'99_ 
1.182   j 
1.166" 

Ratio, 
L  to  D.\ 

mm 

■  ® 

0.976 
0.963 
0.951 

0-939 
0.926 

,v»;4 

46 

_2.-.5S' 2 

2.529        2 

040 
016 

992 
968 

944 
921 
898 

64 
644 

1.842 

1.327 

J.O()l 

46J 

47 
47  i 

1.826 

1.312 

.)-02S 

2.638 
2.602 

2.507        I 

65 

6si 

66 

1.809 
1.792 

1.297 
1.282 

j.()95 

2.485    _i^ 
2.463        I 

2.</)J 

48 

1.776 
1.760 

1.267 
>.253 

2.930 

2.529 

48i 

2.440        I 

66i 

0.915 
0.903 
0.S91 
0.S79 
0.867 

2.S97 

2.494J 
2.459 

49 

2.418        I 

67 

67] 

68 

1.744 

i     ■■7^8_ 
,     i-7ti 

1.238 

'•-23 
1.209 

2.,S6., 

49i 
SO 

50^ 

2.396        > 
2.374        I 

875 
853 
83  > 

2.S32 

2.424 

2.S00 

2.390 
2-356 
2-323 
2.289 

2.2S7 
2.225 

2-353        ' 

68i 
69 

I     1.696 

'-'95 
1.1S2 

2.76.^ 

5' 

2-333        ' 

809 

>87' 

1.681 
1.665 
1.650 

0.856 
0.845 
0.834 
0.824 
0.813 

-•73S 

5>i 
52 

S2i 

2.312        I 

69i 
70 

1.168 

2.707 

2.292        I 

2.272        I 
2.251         I 
2.231         I 

2.21 1            I 

766 

745. 

724 

703 

'683" 

665 

648 

626" 

604 

■•IS4 

2.676 

70i 

1.636 

t.140 
1.127 

2.f.46 

S3 

71 

1.622 
1.607 

2,015 

2-193 
2. 161 
2.130 
2.100 

S3^ 

7ii 

1.115 

-.'•'°3 
1.090 

1.078 

0.803 

2.585 

S4 
S4i 

72 

1.591 

0.792 
~  0.782 

0.762 
0.752 

-■55'^ 

2. 191            I 
2.I7I            I 
2.151            I 
2.132            1 

i       72i 

1-577 
•-563 
'-549 
1-534 

2.526 

S5 

ssi 

73 

2.496 

2.069 
2.039 

73i 
74 

1.066 
1.054 
1.042 

1.019 
1.007 

2.467 

56 

2.439 

2.010 

564 

2.1  13            I 

585 
566 

744 

1.521 

„''S07_ 

1-493 

1.479 

0.743 

2.4 1 2 

i.98r| 

1.952 

1.924 

1.896 

I.S69 

1.842 

I.SI5 

I.7S9  1 

1-763 

••738 

1.712 

t.6S8 
1.664^ 
r  .640 

57 
57i 

2.094            I 

75 

0-734 

2.;,S;; 

2.075            ' 

547 

754 

0.725 

-•35S 

58 

1      2.056     j       I 

1      2.037            I 

2.019            • 

529 
5" 
493 

475 
45S_ 

441 
424 
407 
39' 
375 
.^59 

1.149 

'•'.?4 
1.1  iS 
..103  " 

i,oS8 

^  '-073 
1.059 

76 

,     764  _ 

;    77 

0.716 

2.,\zn 

S8i 

1.466 

0.996 
0.985 
0.974 
C.963 

__o.953 
0-943 

0.922 

0.707 

2.;,oi 

59 

_.'-t53_ 
1.440 
1.426 

~J4'3 

0.1  «>s 

2=73 

59i 
60 

1  6or- 

2.000            I 
1 .9S2            1 

..964    !"1 
1.946        r 
1.028        I 
1.910        1 
1.893        ' 
1.876        1 

:  774 

o.(xS9 

:.:\--. 

!    78 

o.(')S  1 

.'..MS 

784 
79 

o.'i-'; 

-M'l.' 

61 

62 

1.400 

O.Ods 

J.KK) 

1-045 
'■°3'_, 
1.017    i 

O.OC)0 

794 

1.388 
•-376 

0.65- 

2.140 

:  80 

0.649 

2.115 

62i 

63 
63i 

L  8°i 

St 

'•363 
••3S> 

0.912 

0.641 

2.0<p 

0.902 
0.S91 

0-633 

.•.065 

1.859        1 

343 

si4 

1-338 

0.624 

T> 


K 


i 


T/ 


■m 
V. 


TABLE  OI 
AND  ST 
STRESS] 


g 

(« 
Q 


C\.\»*  A 


J 

S-9 

-•i" 

:•' 

•i" 

.S4 

<j.i) 

=r_ 

"S 

i' " 

1                t   ^    '* 

-^ 

!          i.v.> 

» t " 

'5-.5 

^i"^ 

_^  '"-s 

," 

i<)'i 

ir~ 

i__"-5 

.>v'" 

1        25-3 

■_.-«••? 

vi"^ 

I        .?'<' 

}V 

1        35.'. 

M'' 

'      .v^..s 

'*'_ 

4^.« 

■i" 

!         47-1 

li" 

S'-7 

ir 

S<'-5 

rr 

I         (.1.7 

■li" 

1         07.1 

li" 

!     72.S 

ii" 

7S.<) 

li". 

S.So 

^ 

j           1)3.0 

a'" 

i        <)<).  1 

- 1 " 

1  (W  J.  ^ 

-  1 " 

^  1, 

lll.', 

-T" 


I  )0.0 

« 5'>o 


TABLE   XII. 

TABLE  OF  WORKING  BENDING  MOMENTS  FOR  IRON 
AND  STEEL  PINS.  AND  OF  WORKING  SHEARING- 
STRESSES    FOR   STEEL    PINS. 


M 

i 

!        ft 

1     0 
\\" 

>'v 

if 

'*— 
-•i"  ' 

-•r 

-  n 

Resisting   Moments   for   Bending. 

Kl., 

Resisting  Shearing- 
Stresses. 

W 

E 

5 

lUllV. 

Su 

! 
.S|l  l-,!.. 

1 

a.i«  A. 

Cl,i»!>f<                L.ncr.il 
H  Anil  C.      {       Synlcm. 

C'Iam  a. 

Cla»iM;» 

CUu  A. 

CtauMi 
H  and  C. 

1 

3.1 

■I 

! 

'        2.9 

1 

1 

!                .V 

.}•; 

J-o 

\"""  .: " 

8.5 
II.O        , 

'i* 

2j" 

"          _- 

2i" 

2?" 

3' 
3i" 

4.0 

4.8 

1 

5.9 

40                    5.9 

III                     7.2 

~     7,,                   H.S""- 

" 

7.S 
i)..S 

II.S 

1 

■ 
■ 

..     .    «3:3 
12.1              15.2 

7-1 

8.9 

10.6 
12:6' 
'  .4.8  " 
17.2 
19.9 
22.9 

"It              ll--               i3w 

17.2 

8.4 
9.9 

10.5 
1^3 

134 

'f""^     _,         '54 i 

i<r      11       i7-«       i 

19.3 

15.8 

21.3 

-4' 

>>S 

144 

18.4              :vo 

i       18,9 

23.6 

^r 

1        1.1-3    . 

16.6 

21.3 

JO.Il 

20.8 

26.1 

?"^ 

u 

,  Iff 

,vi" 

15-3 

^_  '7-S  __ 
19.9 

1        i2.5 
1       25-3 

19.J 

21.8 

24-5 
28.0 

1       22.9 

28.7 

36.3 

34.'J 

35.1 

3'4 
34-2 
37-' 
40.1 
43-2 
46.5 

34.8       I        29-8 

3 '.8 
36.0 

45.0 

27-3 

38.1 

33-7 

i       29.6 

3t-6 

37-9 

40.5 

SO.C 

1       32-0 

1  3r 

5V 

3i" 
1    31" 
\    3f"' 

,    31" 

i    '♦".- 
!    41* 

'    4i' 
4i" 

4V 

2S.3 
i       .V  <> 

354 

424 

45-3 

5<^-''       i        34-5 

39-5 

474 

50.(1 

(\\.2 

.37- ' 

,?r  i    35-' 

43-8 

S2.6 

56.2 

70.1 

7--f' 
85.() 

39.8 

49-9 

48.5 
53-5 

(..(.J 

6;.  I 

(kS.5 

4».7 

53-4 

ti" 

a" 

42.8 
i  _j47il: 

45.6 

57.0 

58.9 

70.6 

75.4              ')\-: 
82.7             10 -,.11 
90.4             1 1  .;.o 
98.7           >-;v4 

48.6 

60.7 

64.6 

S'-7 
54.8 
58.1 

64.6 

;(i.S                70/) 

68.6 

oi-r                   77-1 
'           72.8                    <)I.O 

7^-7 

107.4 
1165 

134.1       w       61.5 
I4.vi>        i        65.0 

76.9 

81.3 

)J"               iS;.')               lo6.() 

[2G.2              i;-S        '        r.S.;        1         S;.6 

1  vi  ^          1"^''      1      r-'-i      i      'JO-' 

;'■       ji         ()2.0               115,0 

1.17.2       ,       IS4.0 

r  58.(1             M1.S.1 

1       1701             -'13.0 

li        75-8 

94-8 

5" 
'  5]" 
Si" 

5i"       , 

sr   1 

5f 
6' 

! 

it        79-7 

99-6 
104.6 

;J"              1-1.;        i        1;, ;.! 

II        83-7 

>.■■            "1-3 

^V          '■•-•s 

1429 

18.' 0              -':S.7       ''        87 .8 
\tyC,.o             -1-"                9'-9 
;;o(),(i                                   96.1 
_'_\|  0                                  100.4 
1       :!.!>i.'i                            1!       '04-f< 

ro<i.7 
114.9 

15.V' 

1 

6'" 

|i       '5"'" 

1       254-4 

1 
i 

II       .09.3 

i 

^4 


//'  = 

lino  1 
lattc 


> 


ii 


FOADS    THAT     CAN     BE 


iTr.iutwine's  formula.   /('—       ,.„  where 

//'=1(): 

Ti.Mm,  and  in  rij;ht  or  It't't  haiiil  vertical 
line  for  -"r,  and  a  horizontal  line  through  the 
latter,  ir 


8' 

21"      ^       22" 

i                 i 

-3" 

24" 

! 

().o.44       io.3').S 

11.882    1 

13.500    : 

8' 

9' 

10' 

1     7.14')        S.Jii) 
1     5.7.S8    '     6.655 
;     4.7S4         5. 500 

9.3S8    . 
7.604    1 
6.285 

10.667    j 
8:640 
7:141'   i 

9' 

LJ0'„ 
u' 

II' 

1-2'      ] 

{     4.0JO        4.622 
342s        3-98S 

5.281 
4.500    ! 
3.880    ' 

6.000 
'"5,112 

12' 

13' 

!      t4' 

isH 

'4'     1 

2.953        3-396 

4.408    ; 

15' 
i6' 

'7'  "1 

2-573 

2.600 

3-3^0 
2,971 

3.S40    . 

.3-375 
2.9S9 

«5' 

16' 

«7'       . 

2.261 

2.003      ;       2.303 

2.631 

1 8'     i  1     i.7'^7 

2.054 

2.347 

2.667 

18'      1 

>9'  ; 

1.603 

..S43 

2.106 

2-393 

19' 

20' 

1.447 

1.664 

I. (JO  I 

2.160 

20' 

2l' 

i-3>3 

1.509 

1.724 

1.959 

1     21' 

t 

22' 

1. 196 

•-.375 

1.57 1 

1.7S5 

22' 

2.V 

1     1.094    1     I-2SS 

>-43!L 

•-633 

-     23' 

24'    '\ 

1.005  i    '-'56 

1.320 

1.500 

24' 
25' 

25'                0.926     1       1.065 

1. 217 

1.3S2 

26'        :     0.S56    !     0.')S5 

'j'-S. 

1.278 

26' 

27'     h__0:Z?4,_  0.913 
28' J  j    0.73'^  _|    0.849 
29'     1  1    o.6,SS    ,    0.791 

"•043 
0.970 
o.()04 

1.185 

•     27' 

:         28' 
1         29' 

1.102 
1.027 

30'             o.'i.t;;         0.7.(0 

o.S4i; 

0.1)1  <> 

30' 

\' 


FOR     FINDING     THE     S 


■|k 


tads  bciiij;"  those  which  will  ]' 


//'=z]();ul  in  tuns,  //  =  depth  ot    bi'ani  in 

T(i  find  the  sate  ilistribiited  luad  fo 

line  for  k'n^th  of  span.       The  number  fo 

latter,  miilliplied  bv  the  witlth  of  beam  ii 


I 


'       S" 

9" 

10" 

II" 

I. 

8' 

0.  soo 

0.7  r  2 

0.977 

1.300 

I.( 

9' 
1         10' 

o.,v)5 

0-1-0     i 

0.5^3 
0.4  5f) 

0.772 
0,625 

1.027 

~O.S32 

I.; 

I.C 

II' 
la' 

0.2h4     . 
0.222 

0.1  Si) 

o-.i;? 

o-S'7 
0.434 
0.370 

o.CkSS 
0.492 

0..^ 

0-.3I7  ^ 

0.270 

0.7 

13' 

o.( 

14' 

0  1(15 

0.2}} 

0.319 

0.425 

0. 

15' 

0.14.' 

O.203 

0.278 

0-370 

0.. 

16' 
17' 

0.l2t, 
0  I  1  1 

0. 1 7<S 
0. 1 5S 

0.244 
0.215 

o.3-'5_ 
0.2S.S 

0.. 

0-, 

18' 
>9' 

0.01  )l) 
O.O.SI) 

o.u6 

0-I93  , 
0.173 

_  0.257 
0.230 

0. 
0. 

20' 

o.aSo 

0.114 

0.156 

0.20>S 

0. 

21' 
22' 

0  07  ^ 

O.Ottd 

0.10;, 
0.01)4 

0.142 
0. 1 29 

0.I.S9 
0.172 

0. 
0. 

23' 

o.o.S() 

0.1  iS 

0.157 

0. 

24' 

0.079 

0,109 

0.145 

0. 

25' 
26' 

27' 



0.100 

0.123 
0.114 

0. 

._°-°93. 

0. 

0. 

28' 

0.106 

0. 

29' 
30' 

i 

0. 

0 

■-O'-JWp:- 


TABLE    Xlll. 

BINDING     THE     SAFE     UNIFORMLY     DISTRIBUTED     LOADS    THAT     CAN     BE 


BORNE     BY     PINE     BEAMS. 


d^ 


Is  hrin-  those  which  will  pnuhice  a  (Ictlcctinn  ol   only  4^0  "''  ^'^^^  ^P^"'  calculated  hy  Trautwine's  formula,   W  -  |^^.^.  where 

(ins,  ^/  =  depth  (if  beam  in  inches,  ami  / -:--  len-th  of  span  in  feet. 

Ihe  safe  distributed  load  for  any  span,  h.ok  m  tiie  upper  horizontal  line  for  depth  of  beam,  and  in  right  or  left  hand  vertical 
of  span.      The  nuiuber  found  at  tiie  iniersection  of  a  vertical  line  through  the  former,  and  a  horizontal  line  through  the 
led  bv  the  width  of  beam  in  inches,  will  ^i\e  the  load  re(|uired. 


|vSrJ'r'''«(»l 


jr-. 

liiK' 
litti 


'^*Msii' 


..u™^ 


p     LOADS     THAT     CAN     BE 


c'd  by  'l'raut>vinc's  forimi!:!,   //'. 


Mo/ 


.„  whore 


pth  of  l)c;im,  ;in(l  in  ri-lit  or  left  li;iinl  vertical 
Iji,^.  ic  foniier,  and  a  horizontal  line  through  the 

lalte 


I 
') 

20' 

21" 

22" 

23" 
16.531 

24" 

- .  1 

1 
1 

IO.S70 

.2.5S3 

14.467 

.8.781; 

'^  .'- 

.1 

M-SSS 

9.()42 

'•-43' 

r  3.062 

14.841 

9' 

.'■*- 
.''- 

__  6-957 
5-749 

«-053 
6.655 

9.259 

10.5S0 
"S.744' 

12,021 

9-935 

i:__to' 

n' 

7-652 

.-' 

4.831 

5-592 

6.430 

7.347    1 

8.34S 

12' 

,.5 

.|.ii6 
__:v549 

4-765 

_.J.IO(J 

5-479 
..  4-7-4 

6.260   ^ 

5-.i97 

7-"3 
6- '33 

'     13' 

14' 

.'     ' 

3.092 

3-5^9 

4-"5 

4--0J 

5-34;, 

15' 

i'' 

2.7. s 

3.146 

3-'"7 

4-133 

4.691  > 

16' 

i' 

2..(07 

J.7S(, 

3.204 

3.061 

4.1^1) 

17' 

1 
1 

_  -147 

-'•4X5 

2.S58 

3-265 

3-7 '0 

i     18'      1 

r 

_L9i7  _ 

2.231 

2.56; 

2-<)3" 

3330 

19' 

;' 

'-739 

2.013    : 

2.315 

J. (.,,5 

yOO^ 

20' 

'•577    ! 

I.S26    1 

2,0<>S 

2-3W 

2.7  2() 

ai' 

'-437    ! 

1.664    I 

'-9' 3 

2.186 

2.4S5 

22' 

;S 

i-;,'5 

1.522    , 

'-750 

2.000 

-'•--■1 

23' 

'■>5 

i..'oS 

i.3i>S    , 

1.607 

'-\r 

J.0S7 

24' 

/■I 

1,113 

l.2.S,S     , 

I. ,81 

1  .tM(3 

1  .gj  ^ 

25' 

1 J 

1 .020 

i.tyi    1 

>-369    ! 

••565  i 

1.7  7S 

26' 

,s 

0.954 

1.105 

1.270 

1  45' 

i.'M'» 

27' 

,ll 

0.S.S7 

1.027 

i.rSi 

1-34') 

1-533 

28' 

,'' 

o.Sj- 

o,'):;S 

I.IOI     i 

1.258    ' 

1.429 

i     ag' 

.'.) 

*■       .    .      > 

■  N  i ; 

i.rj'i 

'  '"> 

i.r/' 

30' 

i 

Trvs 


FOR     FINDING     THE 


TIk'  loaJs  hciiii^  thosr  whifli  will 

//'--  load  ill  tons,  r/  =  (k'i)th  of  beam 
To  tind   thr  safe  (listrihutcd  load 
liiK'  lor  kn;;tli  of  span.      The  number 
latter,  multiplied  bv  the  width  of  beam 


1 

1 

9' 

lO' 

n'~i 

8" 

0.695 

_9:SSo_ 
0.445 
o.3()8 
0.309 

9" 

10" 

1 

II  " 

1.809 
1.430 

"•157 

_  0.957 

0.804 

0.685 

"  o.59r" 

I 

0.991 
0.783 

0.634 

.^°-S-4. 
0.440 

0.375 

Q.2S2 
O.24S 
0.2IC) 
0.196 
0. 1  76 
0. 1  58 
0144 
0.131 
0.120 
0.tI0 

'•3S9 

1 

■■°74_ 

0.S70 

°-7 19_ 
0.604 

0.444 

0.340 
0.301 

0.241 

0.2  J  7 

o.I97_ 

0.179 

0.164 

0.151 

0.129 

H 

la'    1 

1 

'  _  '3' 
'4' 

'    0.263 
0.227 

- 

1 

15'           o.iijS 

16'           0.174 

1       17'           0.154 

18'          !      0.137 
19'                0.123 
20'              0.  1  1  1 

0.452 
0.400 

o.3.';7 

0.321 
0.289 

■ 

1 

21' 
22' 
23' 
24' 
25' 
26' 

27' 
28' 
29' 
30' 

O.IOI 

0.092 

0.262 
_o^239_ 
0.219 
0.201 
0.185" 
0.171 
o.ifo 
O.I  48 

— 

^w 

'H 

B 

H- 

^B. 

'- 

-"- — 

1 

-..- 

•'^   I 


\ 

i 


TABLE    XIV. 

FINDING     THE     SAFE     UNIFORMLY     DISTRIBUTED    LOADS    THAT     CAN     BE 

BORNE     BY     OAK     BEAMS. 

.a.ls  iK'in-  th.^se  whirl!  will  pnuluc.  :,  (lcfk'cli,,n  of  only  ,i,t  •'»  tli'-  span,  calculated  bv  Irautwinc's  formu'i    IT^     '^'^-     where 

,,,,.,..  '  '  1  1.5/^' 

n  tons,  ^/  =  depth  ol    beam  in  mcho,  and  /  =  length  of  span  in  feet. 

1.1  the  .safe  distributed  load  tor  any  span,  look  in  the  upper  horizontal  line  for  depth  of  beam,  ami  in  ri-ht  or  left  hand  vertical 
,th  ol  si.an,  Ihc  number  b.und  .  the  intersection  of  a  vertical  line  through  the  f.,rmer,  and  a  horizontal  line  through  the 
plied  by  the  width  of  beam  in  inches,  will  give  the  load  reciuired. 


n 

9" 

10" 

1 1" 

_T.8o9 
1.430 
1.157 

0.9S7 

0.804 

0.685 

'  0-59''" 

0.452 
0.400 

0-357 
0.321 
0.289 
0.262 

0.^39 
0.219 
0.201 
0-185 

0.1  f)0 

0. 1 4S 

,2" 
2.34S 

'3" 

i        14" 

1 

■5" 

16" 

■7" 

18' 

19" 

20'' 

1 

21" 

22" 

23" 

24"     1 

^s. 

0.99' 
0.634 

0.440 

o-37_.S 
0.32;, 

'•3S9 
'•°74^ 

0.S70 
0.719 
0.604 

"oTsfr 
0.444 
0.386 
0.340 

0.301 

0:26s" 
0.241 

0.1  <)7 
o.i7<) 
0.164 

J=-9^*S_, 

__3'7-S 
2.946 

4-5«S 
3-623 

5-565 
4-397 
.J-562 
2.944  ^ 

6.675 
S-274 

__4-272 

3-53' 

7.924 

9-3 '9 

__7-36j^ 

_5-964_ 

4.929 

_4:^'4L 
3-529 

' 

IC.S70 

'  S.5S8 

6.957 

5.749  ' 
4.S31 

4116 
_J-_549 

3.092 
^2.718 

_„-l407~_ 
__2a47 
1.927 
'•739 
'.577 
'•437 

_I2.583 
9.942 
8.053 

_L4_467_ 
11.431 

9.259 

J6.53'_^ 

13.062 

10.580 

8.744 

7-347 

18.783    ! 

_i4.84i ; 
12.021  ! 

9.935  ' 
8.348 

8' 
9' 

>io 

'-"^SS    i    2.359 

6.261 

_5-o7i^ 
'4.191 

MS 
j68 

1  50;,        i.'in    i     2.386 

2-93S 
2.425 
2.038 

to' 

J.242    ,     1.579 

1.972 
.'■^57  _ 

6-655 

7-652 

II' 

12' 

joy 

1.044 
0.889 
0.767 
0.668 

1327 

2.474 
2.108 

2.967 

3-522 

_-5:.S9i_ 
4-765 
4.109 

6-430 

1. 130    '     1.412 

«-737 
1.497 

2.52S 

3.001 

5-479 

6.260 

7-"3   ' 
6.133 
5-343   \ 
4.696  i 

4-159   1 

13' 

-!/ 

C.849 

1.217 

1.817 

'-5S3 
_l'39i 
1.232 
1.099 
0.987 

2.179 
..899 

2-5S7 

"=54 

3-043 
2-651 

4-724 

5-397 

14' 
15' 
16' 

17' 
18' 

9A 

0.282 
0.24S 
0.2 19_ 
0.196 
0. 1 76 

1.060 

_'j.3°4_ 
1. 146 
1.015 
0.906 

3-579 
3.146 
2.786 

4.115 
.3-617 

4.702 

74 

-_9-5^7,.    _^°-74''> 

0.932 

1.669 

T-478 
1.318 

1. 98 1 

2.329 

4- '33 

.vt 

0.520      0.661 
0.464       0.589"" 
0.4 1()  ,    0.529 
0.376      0.477" 
_o.34i    !    0.433 
0.31 1    1    0.395 
0.284   j    0.361 
0.261    i    0.332 

0.826 
0.736 

•-755 

2.064 

3.204 

3.661 

Si 

1-565 

1.841 
1.65: 

_2-4«5_ 
2.231 

2.8  58 

3-265 

2-93' 
2.645 

3.710  1 

3-330 
3.005 
2.726 

2.4fi5 
2.274  ' 
2.087 

;    1-92.? 

!     I-77S 
1     '-649  , 
'     '-5.13 
UM29.| 
'■3,'/> 

11. 

0.661 

0.813 

r.183 

1.405 
1.268 

2-565 

19'      ' 
20' 
21' 
22' 

23' 

24' 

25' 
i     26' 
1     27' 

r  28' 
r  29' 

ti 

^  0..58 
0  1 44 
0. 1 3 1 

0.t20 
O.I  10 

0.596 

0.541 

^  °-493  " 

0.451 

0.734 
0.665 
0.606 

_°;S09, 
0.470 

0  434  _ 
0.403 

__o-374 
0-349    i 
0.  ^.-6 

0.891 

1.068 

1.491 

2.013 
1.826 

2-3'5 

01 

0.808 
0.736 
0,673 

.0:969^ 
0S83 
0.808 
0.742 
0.684 

1.150 
""1.048" 

1.23: 

2.098 

2-399 

'.)-' 

1.664 

'•9'3 

2.186 
2.000 

— 

0-959 

0.881 

1.12S 

'•3'5 

1.522 

'-7  50 

0.1  51 

0.411 

0.617 
0.570 
_o.527 
o.4,S9    1 

__o.454    i 
0.424    ! 
c.  ;ci'i 

'■03i 

1.208 
1.1 13 

1 .02() 
0.954 

O.8S7 
0.827"^ 

1.398 
..288 

1.607 

'•837 

0.129 

0.240        0.306   1     0.3S2 

0.222            0..'S2             0.353 

o.joii        0.2(12    ;     0327 

0. 11)2           O.J).(     1       0.304 

0.81 1        0.954 
0.750        0.88: 
0.696    ;    0.8 i.S 
0.647        0  761 

.48. 

1.369 

1.270 

"1.181 

1.693 
'-565 
1-45' 
1-349 
_'-A58  _ 
1.175 



0.632 
0.586 

.  °-S45 
0.508 

0.4- q 

1. 191 
1. 105 

1.027 

J_p.95S3 

0  S()5 

0.17') 

o.-'j; 
c  -'  1  • 

0..-84 

0.603  ; 

0  563 

0.700 

l.IOl 

l.02() 

Pa 

Let 


i  I 
I 
I 
I 
1 
1 
1 
1 
I 


\' 


\ 


i 


OF   CLASSES  A  AND   B 


"  ^  ,  /•'! 


12";  ami  ^iiard  rails,  6"x6 


Pa 
Ler 

I 

I 

I 

> 

J 

1 

Roadway, 
24'  clear,  j 

'"  '  i 

1 201 

No.  of 
Joists. 

•3 

Size  of 
Joists. 

,5"  X   10" 

No. 
rai! 
per 

Hand- 
Posts 
panel. 

Panel 
Length. 

!0' 
11' 

12' 

I 

'3' 

14'       1 

1 

15' 
16' 

17' 

18' 

19' 
20' 
21' 

,    ,3/ 

24' 

•y 

1382 

I4S4 
1710 

>3 

\  3"  X  10" !' 

>3 

3''X'o", 

3"  X    12"    1 

13 
'3 

— 

1782 

i      y  X    \2" 

205() 

2136 

•S 
•3 

'      3"  X    '2"     1 

3">^'4" 

-tX) 

;,oSo 
3339 

»S 

3"  ><  14' 

16 

1    3"  X  14* 

I          4 

'S 
17 
14 

4"  X  14" 

1 
"•         1 

4    ,      ' 
i 

4«x  14* 

467 -• 

J 

4*  X  16" 

6 

16 

1      18 
20 

4*  X  16* 

6 

j     4'  X    16" 
4"  X    If." 

\         6 

m 

-.  I 


"K 


i 


TABLE   OF   PINE   LUMBE 


I'loorin-  3"  thick;  hand-rail  \u 


Panel 
Length. 

Roadway, 
12'  clear. 

No.  of     Roadway, 
Joists.      14'  clear. 

No.  of 

Joists. 

Road 

16' cl 

10' 
II' 
12' 

691 

776 

1 

8 

sr 

806 
842 

'}02 

1        944 

S 
8 

i      99 

i          10.) 

'3' 

i        990 

1 1 10 

S 

'  -.\ 

W 

lOJd 

7    ;    ..5^ 

S 

'-7' 

15'      ' 
16' 

1  rSo 
'--I 

•.^'S 

9 

8 

\       '45' 

<,57f> 

,yj 

17' 

18'   ! 
19' 

1  |00 

MP 

i 

TV, 

8 

'5('5 
1670 

9 

Tjc 

10 

lS,,i 

8 

I      1950 

9 

2 '57 

20' 
21' 

1 
')       1 

i      2aS5 
2177 

1 

.0       1 
S 

2.V)2 

7       1 

J  (20 

22' 
23' 
24' 

1 

S 

2.536 

9 

25«5 

10 

27S« 

3024 

12 

.15 -S 

OF   PINE   LUMBER 


TABLE   XV. 

REQUIRED   PER  PANEL    IN    BRIDGES  OF  CLASSES  A  AND    B 
(including  waste  material).  a  ainu   ti 


.rin^  3"  thick  ;  han.i-ail  posts.  4"x6"X4';  hand  rail.  tw..  pi.ccs.  3"x6";  huh  rails,  y'x.:";  and  .au 


■A^ydn]  rails.  6"x6'' 


1 

3.  of     Roadway. 

if^ts.      14'  clear. 

1 

No.  of 
Joists. 

Roadway, 
16'  clear. 

1 

7 

776 

8 

sr.i 

7 

902 

8 

i . 

8 

S 

9 
8 

1      998 

7 

I        944 

i     1046 

7 

IIIO' 

I  j;,o 

"              "5^ 

1278 

s 

i;,iS 

'4S<J 

;- 

>37<'' 

■  S2S 

i 

9 
10 

1730 

J 

1670 

.84, 

! 



1950 

2aS5 

2177        1 
2336 

9 

10       i 

8 
9 

-'5; 

2.(20          j 

) 

ir 

1:;       i' 

■^1 

30-4 

No.  of     Roadway,     No.  of     Roadway,    No 
Joists.      18'  clear.      Joists.      20'  clear. 


II 


Ro 
24 


\ 


> 


IDGES    OF    CLASS    C 


2" ;  and  ^aiard  rails,  6"xC)". 


Roadway, 
24'  clear. 

No.  of 
Joists. 

Size  of 
Joists. 

No.  Hand- 
rail Posts 
per  panel. 

Panel 
Length. 

IJOI 

'3 

,?"  ^  10" 

r  „ 

1      3"   X    10 

10 
II 

i;,S-' 

•3 

'454 

'J 

j    3"  X  'o" 

13 

13 

ifiii) 

'3 

!  3*  X  '0'  ; 

1  lyio 

«3 

1    3'  X  12*  i 

3"  X   >2" 

4         ! 

»4 

— 

13 

«5 

jrsS 

•5 

3"  X  '^" 

16 

-',5^7 

'3 

3"  X  14* 

1      '7 

:4f)2 

14 

3"  X  14" 

'>           4 

1      18 
20 

-     1 

3730 

15 

3'  X  14' 

^'/■J 

>3 

4'  X  14* 

3393 

>3 

'     4'  X    If/ 

6 

21 

1 

3465 

'^ 

:    4'  X  16' 

6 

'      22 

.V"!.?-' 

'4 

4"  X    16"    , 

' 

23 

.)I(K3 

.6 

i    4'  X  16' 

!        ^ 

I      24 

J 

^ 

1 

TABLE     OF    PINE     LUMBER     REQU 

(inclu 

Floorinj;-  3"  thick  ;  hand-rail  posts,  4"x6"X4';  ha 


Panel 
Length. 


Roadway,    No.  of     Roadway,    No.  of     Roadway,    No.  of     Roadwa 
12' clear.      Joists.    ,  14' clear.      Joists.    1  16' clear.      Joists.      18' cleai 


10 

11' 
12' 

13' 
14' 
15' 
16' 

17' 
18' 

19' 
20' 
21' 
22' 
23' 
24' 


691 


SoO 


S42 

94' 

ioj6 

ijif) 


I  s  ^'1 


IO.S5 

1 

7 

"133 

7 

|()fX) 

7 

2236 

S 

■ 

rrC' 

s 

902 

8 

944 

8 

ros4 

8 

..5.^ 

8 

1270 

8 

1360 

9 

1502 

8 

1   1544 

8 

1740 

9 

I- 


1899 


2400 


2ri7 


2502 
2672 


8 
8 
8 

9 
10 


86; 
998 


1046 


1 167 


1278 


1408 


1504 


1667 


f7'S 


1924 

2II2 


2420 
24')S 
276S 
2944 


9 
10 

9 


10 


9 
10 


94'' 
1094 


II4S 

12S0 
1404 

■;       '5t'' 
jl        \(<.\S 

■  1 

I       iSS() 

2178 
2325 


2663 

-7K 
.)034 

33 1 1 


TABLE   XVI. 


LUMBER     REQUIRED     PER     PANEL     IN     BRIDGES    OF    CLASS    C 
(including  waste  material). 

id-rail  posts,  4"x6"X4';  hand  rail,  tw  pieces,  2"X6";  hub  rails,  2"x  i:";  and  guard  rails,  6"x6". 


of 
ts. 

Roadway, 
i6'  clear. 

j                -, . 
86 1 

!      998 

No.  of 
Joists. 

9 
9 
9 

Roadway, 
18'  clear. 

94C 
1094 

No.  of  : 
Joists. 

Roadway, 
20'  clear. 

No.  of 
Joists. 

M 
II 
II 

Roadway, 
22'  clear. 

1116 
1286 

No.  of  , 
Joists. 

12 
1 2 

Roadway, 
j  24'  clear. 

1:01 
13S: 
'454 

No.  of 
Joists. 

'3 
•3 
•3 

Size  of 
Joists. 

_„..     _.._.__. 

!     3"  X    10" 

No.  Hand- 
rail Posts 
per  panel. 

1 

1          2         i 

Panel 
Length. 

10' 

10 

1031 

ro 

1190 

3"  X  10" 
3"  X  •o" 

i 

4 

1 

:      4 

1      11' 

1 

12' 
13' 

1046 

1148 

ID 

10 

10 

1250 

•352 

it67 

9 

0 

1280 
1404 

•393 

II 

•504 

1656 

1      .822 

19S4 

12 
1 2 

1O19 
i-S: 

•3 
'3 

;  3"  X  10" 

4 

1278 

•530 

II 
.. 
12 
II 
12 

i     3"  X   12" 

4 

14' 

1408 
1504 
1667 

9       i 
10 

'^       i 
9       1 
.0       j 

1       '546 
164S 

.8J2 

10 

1684 

'79- 

12 

14 
12 

i960 

:i:S 

•3 
'5 
•3 

'    3"  X  12" 

!        4 

15' 

1 1 

3"  X  12" 

4 

1 

i6' 
17' 

10 

•997 

2162 

'-r-7 

3"  X  14" 

4 

•7'S 

;   1886 

10 

2120 

2291 
2546 
2752 

•3 

2462 
-730 

14 

1     3"  X   14" 

4 

18' 

! 

;     1924 
2112 

2.78 
2325 

12 

2362 

•3 
II 

•4 

•5 

i    3"  X  14" 

4 

19' 
20' 

j 

9 

10 
10 
10 

2539 

2965 
3393 

•3 

1    4"  X  14" 

4 

2420 

>       24C)8 
276.S 
-944 

10 

1 1 

'   2663 
2:17 
.1034 

.vV14 

2907 

II 
II 

1  ** 

3150 

,      32.6 

35(if' 

1 2 
12 
•3 

'5 

•3 

;     4"  X   16" 

i 

6 

21' 

22'      1 

i 

1  . , 

1 

' 

2967 
3300 

'    3465 

•3 
'4 

16 

4"  X   16" 

6 

II 

'3      i 

4"  X  16" 

6 

6         1 

i 

3616 

•4 

3S88 

!     4"  X  16" 

I 


\ 


I 

I    VluvA 
!  Length. 


'9' 


T^  PANRIDGES  OF 


joists  and  llo'y.i'.  i, ,  ;,.„         „ 

puard-rail,  6")  ^^'  '''''''''  ~^''''  '^■■'>  ^.11,  .V'xr.v 

The  upper  fij   ^vaste  , 


Pan.-l 
Ltnglh. 


Roadway, 
12'  clear. 


No.  of  ).  of  I      Size  of       No.  Hand-     „ 
Joists.  lists,  ji    Joists  rail  Po?ts      Panel 

I  "        per  panel,    length. 


\ 


TABLE   OF   PINE   AND   O. 


Joists  and  floorint;'  of  oak,  and  other  lumber  pine 
an  1  f;uard-rail,  6"X6''. 

Tlie  upiKT  figures  in  each   rectangle  are  for  pin 


- 

Panjl 

Roadway, 

No.  of      Roadway, 

No.  of 

Roadway, 

N 

1  Ltngth. 

i 

12'  clear. 

Joists.  11  14'  clear. 

Joists. 

16'  clear. 

Jc 

1 

1  51 , 

;      117 

/ 

'         1  ;<> 
•1S3 

S      ! 

,56 

550 

1 

200 

200 

8 

200 

'      .\>^^ 

7 

5f'5 

G43 

f 

1            JOO 

200 

8 

1 

200 

i  "' 

■>35 

7 

620 

70s 

;            :jS 

22S 

s,  1 

22S 

'3' 

1      61s 

7 

712 

S09 

'        :!j.S 

2  28 

8 

22S 

'l' 

-5" 

7 

7 

770 
256 

«75 

^ 

,       i 
S 

256 

'5 

730 

1       S45 

960 

,  , 

j;() 

1 

i       7 

25.) 

8 

256 

'  " 

^1(1 

944 

1072 

, 

JS,( 

2.S4 

8 

284 

'7 

ciJO 

/ 

;      loll,; 

1207 

f       i8' 

JS4 

284 

8 

284 

i».Si 

,       / 

1      "34 

1287        1 

'9' 

3'- 
1142 

7 

1      >3'8 

S       i 

i 

3'2 
"495 

•o' 

3'- 
1-53 

7 

1        312 
1447 

8 

3'- 
1640 

, 

35'> 

- 

r^s" 

s 

356 

1-100 

/ 

;      "''5 

lS;,o 

22' 

35" 
1  fii 

3^4 

7 

35'> 
1709 

3^4 

8 

,                               1 

^        35<' 
,      '93'^ 

, 

1        7 

'       8 

384 

'^J 

1  ;S() 

1S29 

2072 

Vi-t 

11S4 

3«4         1 

^V 

'"11 

1992 

9 

1 

2368         1 

TABLE   XVII. 


OF   PINE   AND   OAK   LUMBER   REQUIRED   PER  PANEL  IN   BRIDGES  OF 

CLASSES  A  AND  B. 


oak,  and  other  lumber  pine.      Flooring  2.]"  thick;  hand-rail  posts,  4"X6"X4';  hand  rail,  two  pieces,  2"X6";  hub  mil,  2"X  12 
:ach  rectangle  are  for  i)ine,  the  lower  for  oiik.     The  ciuantitics  include  waste  material. 


oadway, 

.'  clear. 

1 

No.  of 
Joists. 

Roadway, 
16'  clear. 

No.  of 
Joists. 

Roadway, 
i8'  clear. 

No.  of 
Joists. 

Roadway, 
,  20'  clear. 

1 

No.  of 
Joists. 

Roadway, 
22'  clear. 

No.  of 
Joists. 

I  "^ 

Roadway, 
24'  clear. 

1 

1 

No.  of 
Joists. 

Size  of    ' 
Joists. 

1 

No.  Hand- 
rail Posts 
per  panel. 

2 

Panel 
Length. 

1  ;(> 

8 

156 

200 
643 
200 
705 

9 

'J       i 
9 

0      ! 
9 

If- 
617 

10 

156 
683 

1        200 
798 

II 
II 

'50 
750 

'5'' 
Si  7 

13 

2.!"X8" 

2i"Xl0" 

10' 

200 

8 
8 

200 

200 
790 
228 
906 

10 
10 
10 

200 

875 

1       -°° 
'      953 

13 

4 

XX' 

ta' 
13' 

14' 
1     '5' 
'     16' 

1  ■/ 

200 
620 

200 

87.5 

228 
i       '003 

32S 
10S5 

256 
1190 

256 
1328 

1        284" 
!       '494 
i         :S4 

.    '^"3_._. 
i       3'2 

i        3'2 
t      2027 

'        356 
2260 

:     "356    '" 

__239L 

384 

255« 

•        .3«4 

2Sd., 

II 

200 
960 

I  2 

1       200 

!    '045 

13 

4 

22^ 

7'- 

'-'s"\ 

228 

1          800 

II 

22S 

IIOO 

I  2 

1 2 
I  "* 

228 
1197 
22S 

r2.,5 

»3 
13 

2|"Xir'    ; 

1 

4                 ; 

2JS 

770 

"      1         960 

8       '         =56 
i        1072 

S                 '^^ 
1207 

^'    .              "284"" 
'^               1287 

8       i!        3'  = 

228 
9S0 

j~     256  ~~ 

'075 

1200 

'""' Is.i  ■'" 

1  ',;o 

10 

10 

I  i 

2J8 

1     1190 

2^"X  12" 

4 

1 

2's,6 

9 

1 

9      1 

II 
II 

I    256 

1    1305 

!         2S6 
i       '4.56 

!"""2^6 
1       'I'O 

2^6 

1 5.S4 

'3      i 
13      ' 

2.|"XI2" 

4          1 

i 

250 
944 

10 

I  "^ 

3"  X  12"  ! 

.1    1 

28., 

10(1; 

9 

9 

10 

II 

i         284 

1       1637 

284 

1746 

312 
2025 

I  "^ 

1       2S4 

'     2S4 
1S99 

•3 

3"  X  '3" 

^    ! 

~28r' 

1 1  "i.i 

2S4 
;      14.10 

3'- 
_  1672 

'833 

356 
2045 

356 
i      21(1? 

.vS4 
23 '5 

3^4 

.'did 

10 
10 

11 
II 

I  2 

'■' 

3"  X  '4"  j 

4 

1      18' 

;.'- 
i;i^ 

12 

i         -''2 
i       2202 

13 

3r'xt4"  : 

4 

1      ''' 

\     20' 

1 

21' 
22' 

!    23' 

.V- 
1 1.1" 

J 

8 

31- 
1640 

""  356" 

!      1830 

:     35" 

i       '93''' 

i     9 

10 
10 
10 
10 
12 

3'2 
2220 

35'' 

;     2475 

i        356 
i      2O18 

1        384 
2801 

384      ^ 
3112 

I  2 

3' 2 
'       2.113 

13 

4"  X  14" 

^ 

.>.=;|' 

S 

1 — ^ — 
9 

9 

1     9 

1 1 
II 

11 

I  2 
1 2* 

14 

20i)O 

'3 

4"  X   ,5" 

6 

■'      35(i 
1     2845 

3^4 

'     3044 

384 

33'JO 

13 

.     4"  X    16"    1 

i 

4"  X  16" 

6 

350 
1709 

8 

•3 

!          6 

3^4 
1H29 

.3''^4 
•  99- 

8 

i        3S4 
2072 

3^4 
2368 

9 

1 1 

'3 

15 

4"  X  16" 

6 

24' 

r  n 


\ 


Panel 
Length. 


10' 

n' 

12' 

13' 
14' 
15' 
16' 

18' 

19' 
20' 
21' 
22' 


I 


23' 
24' 


i 


ANEL   IN   BRIDGES 


loistshand  rail,  two  pieces,  2"xCi"\  luib  rail,  2"x  i-"; 


iiul  oriKirc 

atcrial. 



Panel 
Length. 

lo' 
ii' 

12' 

pof 

,ts. 

1  • 

Roadway, 
24'  clear. 

No.  of 
Joists. 

Size  of 
Joists. 

No.  Hand- 
rail Posts 
per  panel. 

i 

2 

Panel 
Length. 

156 

200 

200 
101;, 

228 
1159 

228 
'-57 

256 
1420 

2  5(> 
I. (So 

2.S.1 

1722 

2S4 

.1'- 

20  so 

22(12 

.55" 

2SlS 

35" 
2757 

3«4 
,i'04 

>3 

i      2J"X8'' 
2 1 "  X  9" 
2i"X9'' 

1 — -     -  - 

i      2i"Xll" 
2j"X.2''    i 

10' 

I.? 

4 

11' 

12'' 

13' 

14' 

15' 

16' 

17' 

4 

1 

13'         j'    ' 
14' 

15'      :    ' 

13 
'3 

4 
4 

4 

1 

•3 
'3 

■3 

1 

j        16' 

1 

!      17 

1    I 

! 

1       » 

2j"X  12" 

1     3"  X  '-■' 

1       ,    -        .  -    - 

i     ^    ^  '-^ 
;,"  X   14" 

3^X14" 

!     3i"=<'4' 
'     4"  X  14" 

;,    4"  X  16" 

4 
4 

i      '«' 

i          4 
4 

1          4 

18' 

19' 
1      20' 

'3 
>3 
14 

:  19' 

ao' 

2a' 
23' 
24' 

21'     '    5 

1 

22'      i    5 

1     . 

23          - 

1 

6 

•4 

'3 

'          6 

!      6 

24' 

!  2 

4"   X    !()" 

:  '  6 

If 


JS 


TABLE   OF   PINE   AN 


foists  and  tloorin^^  of  oak,  and  other  lumber 
iiid  jTuard  lail,  6"x6". 

The  uiipcr  tiguix's  in  each  rectangle  are  for 


1 

Panel 
Length. 

Roadway, 

12'  clear. 

^ 4j7 ' 

200 

,88 

1         200         i 
i         S.8         I 

228 

594 

22S 

64^ 

-5" 
730 

-.56 
760 

2S4 
,          888 

1         284         , 
950 

312         i 
'       1060 

3'- 
1 172 

35" 

I2V) 

1  s 

'          3^4 

1586    _ 

384 
1616 

>4o.  of      Roadway, 
[oists.      14'  clear. 

No.  of 
Joists. 

8 

Roadway 
16'  clear 

lo' 
11' 
12' 
13' 
14' 
15' 
16' 

17' 
18' 

19' 
20' 

21' 

22' 

i 

23' 

24' 

7 
7 

156        i 
4.S3 

,56 

550 

200 
565 
200 

()0O 

228 
688 

8 

200 
643 

8 

200 

r,83 

7 

8 

228 
783 

"y"\ 

228 
747 

8 

228 

849 

,  1 
/  1 

7 
7 

256 

'        845 

2  -^0 

j       8S0 

284 
1027 

\"     ^84 
1098 

8 

8       ! 
8 

960 

-"256 

1000 

j        ^84  " 
;       I i(>6 

2S4 

;     1-46 

7 

3>2        i       8 
1225 

3'=        i       8 
:       >353       J 

3>2 

i390_ 

3'2 

"  535 

7 

35"         '        8 
'       1  '!44 

356                 9 
;       'f^94„_    1. 

384         i        8 

'829     ;  ^ 

35*' 
■738 

8 

7 

35" 
1907 

384 
2072 

7 

3M                8 

1S(,., 

384 
21 12 

— 

TABLE   XVIII. 

JLE   OF   PINE   AND   OAK   LUMBER  REQUIRED   PER  PANEL  IN   BRIDGES 

OF   CLASS   C. 

ol  oak.  and  other  lumber  pine,      iqooring  2,1"  thick  ;  hand-rail  posts,  4"X6"X4';  hand  rail,  two  pieces.  2"X6";  hub  rail,  2"X  12"; 
in  each   rectangle  are  for  pine,  ihe  lower  for  oak.     The  cjuantities  include  waste  material. 


Roadway, 
14'  clear. 


No.  of 
Joists. 


Roadway, 
16'  clear. 


No.  of     Roadway,    No.  of 
Joists.      18'  clear,   i  Joists. 


Roadway,    No.  of    I  Roadway, 
20'  clear.     Joists.      22'  clear 


No.  of 
Joists. 


'  '  ..,        i-    '     c-         £       No.  Hand-     p__.i 

Roadway,    No.  of  1      Size  of        ^^-^  p^^j^      Panel 
24' clear.     Joists.  I      Joists.        ^^^  ^^^^^j     Length. 


Panel 

Length. 


lu  I  '      I 


i 
I 


J 


ti"».i»jM 


f 


Panel 


Ituiltlicim,  ().'#  |)fr  fool 

Wcl),  yx-^o" 

ir.>  fl    1  -.1 "  V  ^^  -  -tt.  -. 


lUiilt-hcmii,  ().)J#  |)ti  foot 

\\t\,,\"XT,0" 


.«' 


i 


.''■'     !  Kiij.lw.iv.  li   I'li.ir 


1..-  t.«I 


I.'"  (-■•I 


;  v>«  I. . 


!.•"   (.■•I,  Ml  l<,'  V.«I,  ,M 

I  lliillt  lit'.iiii,  |i«  |iii  liuit  lliiill  In.iiii,  I 

Wdi,  I'xi.)'  Wil..  J"<jj 

l'|i.  ll., .'  j"x  .'J"  \.%»  .in«li'  \  I'll.  rt..  i  :' ' 
I.,  rt..  1  -•' X  r  |«  .mull'  I-  H„  1  j'X  1 

JIJ"     l.'«I.    Ml  !<.'    V>«I,   Ml 


""!'  t"!«I 


I  •■,,.•«  I,... 

i;. III!  III. nil.  r!*  I"  I  '■•■•< 

Uih.  I'X  |S' 

I  I'll.  -•  j"x  .•!"  V5«.im'.lf 
I     ll ,  J  .'"x  ;(•  \  «•  mull' 

ly   I--*!.  ■'! 
IIiiiIi-Ihmiii.  I'll*  I'll  I. Mil 
W.I,,  i'x  |S- 

I  I',  ll,,  .'  .'"x  Jj"  IS*  .iiiuK* 
I     ll  ,  -•  •■•'  ,r  .|«  .inuli' 

!.•■  I-'*!.  Ml 

I'llllt  Ih'.IMI,    |I«  |»I    ImmI 

Uil.,  l"x  i,|' 

I  |.,  It.,  -•  .•'xjl"  vi;«.iiinli 

I    ll,  .'  :    »  i"  i«  .iiiulv         I 

!.•■    (-■•I  Ml 

r.iiilt  Ikmih.  i-'l*  pit  l"il 
W.I.,  I'x.m" 

I  i-  ll,  i  J'x.'}'  ?;«,inKi> 
I    ll .  .•  .'"x  i' .()»  ,llllilt• 
|y■|-•»I.  Mr  I 
laiili  Ik.1111,  44#  |ur  I'm..! 

Will,  [-x.-r 

I  p.  ll,  .•  .•'x.-J'  1  ;»,lll^lr 
I     ll  .  -•  j'X  )•  4«  .lin;k- 

I,"  ;r*I,  .M 

|;  nil  1.1-  nil,    i;*  I'll  ImmI 

Wil.,  l"x  jj' 

I  |i.  ri,  J  J'x.'i'  i.;#4iinlr 

I  .  rt.,  J  j"X  i'4«,iiikU- 

I ;'  no*  I,  M. 

Iiiiili-l'f.iiii,  |''1»  |iir  (,"'! 
Wtl.,  ('xji' 

I  p.  rt.,  .•  2"xjj"  v.s**"*;!'' 

I  I.,  rt..  .:  -•'  ~<  ',"  1»  -I'luli- 
1 5*  ^'^  !•  '' 

Hiiill-U.iin,  !*<«  pil  (m.,1 
W.I,,  >'xj(' 

Ip,  A.,1  l''  4"  )■$»  .ingk' 
I  ,  rt  ,  ;  j"x  r  i«  .iii»!U' 

i;'  5o«  I.  Ml 

liiliil-lif.llll,    \<0  piT  ImmI 
Wil..  \-  '  2S" 

I  p.  rt., :  j'X  •["  y!i»  .inKk- 
I    ll,,  ■  .''X  ;■  .|«.inf;lc 

k"  ;,*I.  Mf 

l;ilill  Inaill,  V*  |»1  fMMl 

Wtl.,  y  Jl," 

Tp.  rt.,  J  J"x  jj"  v,S*'i»".l'' 

I  ,  ll ,  .'  .-'x  (•  4#  .iiikIi; 

I ;"  50»  I,  iir 
,  P.iiilt  l.iaiii.  V*  i'l'i  f""' 
Will,  l"x  .-s" 
I  p.  ll.,  ;  j"x  i".l«.iiiKle 
I     ll,  -•  .'i'x  i'.).!*:"!),!!' 

1  ;■  ?,-.«  I,  Ml 

Pun!   Ik-.IMI,   5-'#   plT   ImmI 

WM.,  l"x.>fi" 

I  |,,  rt.,  J  i'y  \'  ,|«  -injiii' 

I,  rt  ,  J  .'J*  '  ;"  I  4».in«lt'^ 

P.inli  1.1 .1111,  ;;«  pit  (mm! 

\', .  I..  J"x  :r' 

1    ;,    ll  ,  .•  j'X  ('    |«  .iiml'- 

I     ll.,  J  .•4'xj"4.,|#.iii«l>.- 


I  J"     l.'«I.    Ml  is"    V1«I,   Ml 

llllill  l,t' nil,    |.'|«  pir  ImmI  llllill  I'l.llll,   ; 

Will,  I'X. -o'  ;  Wl-ll,  J"X;| 

I  p.  rt,  -•  .'"x  jj"  j,5«,innli.    I'p,  A.,1  j"» 
I.,  rt,  -•  J*x  ,"  |II,iiikIc  l,.rt,.»j"x 

ij'4J»I. 


I  J      4J»  ^,  Ml 

I'llill  lit'.lln,  ,|  I*  pil  ImmI 
Will,  I'X.i 


'iS'SO#l.Mi 
llllill  lit.iiii, 


A.i  Will,  I'X.'-, 

I   p.  rt,. -•  J'X.'J'  4.s«,lll|;lr     I'p.  rt.,  J3"' 

I.,  rt.,  -•  .-'x  \-  i«.iihu-         I.,  rt., :  j"x 

'5*  so*r '" 

llllill  In'. nil,  (S*  pii  Im..i 
Will,  l"x  ..•" 


|,'50#I,, 
Iliiill'liiMiii, 
Will.  I'xj 


Will,  l"x  ■:•  Will.  I'X  ji 

rp.  rt., .'  j'x.'i"  vs«,i"hI'    I  p.  rt.,  ii'' 

1.  rt..  .'  i"x  V'  («.inKli'  I.,  rt.,  JJ'X 


.  5"*  I.  ■ 
Itiiili-hiatii, 
Will,  |"X;i 


lluili  1,1  .nil,  ,|i*  pn  ImmI 

Will,  I'x.v,'  Will,  |-X;i 

I  P  rt.,  -•  j'x.M"  v-,«.iH.;li  Ip.  rt.  ja": 

I.,  rt,  .'  j'X  ;,•  («.ihKl'  I  I-  rt.,  2  i|'' 

!<,'  ;m«I,  MI  . 

i^iuiiLi.*..  i^!«p.M-.  '"'•'?:•"'• 

W.I,,  I'X  js-  ^'''■' '*: 

i|-.".---'-«-'!'.v^*'^"«i^'  ,'',,  :',r, 

I.,  rt,.  J  J'x.)'.t)»,iiiBle^  ^1.  II.  .  Jj 

It*  (o*T,  iir  I  ,.  .,  , 

.1    i.i          .»«  .    i  f    .  llllill  lii.nu, 

lluill  lii.llll,  <0»  pir  ImmI  j 

Wil.,  i"<Jli'  ill          .' 

Ip,  rt,JJ■x.•l',s«.l„^u■|    l"'■•;; 
l,.H,.  jj'x,'.,«.i„nk  ji-".-'-  >« 

i;"  ;o»I.  Ml  I     . 

,,     ,    ,                -         .      .  I'.inlt  I't.im. 

liinli  l.r.nn,  5I«  I"  I ....     ,.^  , 

......           •  I  \\  ill,  1    X  J, 

l-p.rt,.Jj'x.,"  ,«.nu,l.-  :      ',,     ."^^^ 
I.  rt.  J  Ji'M^l  |»  .m^;lc  J '""••■ -^  '■_ 

I.'Vf^'"'.    I  ,  '""iit'-". 

\v''h,rx';.r'"  ;\vci..rx,. 


Ip.  rt,  J  J"x  ^'4».iiikIc 
I,  rt  ,  J  Ji""  r  I  1*  •mull' 

llllill  Iv.iiii,  ^;»  p.r  f.i.il 
W,|..  I'x  j; 

I  p.  rt  ,  J  j'X  i'  4«  .mt'.li' 
I.,  fl.,  3  Jl'X3•4.4».^nBl'-■ 


ll>.  rt.,  J  j" 
I.,  rt.,  J  J"x 

IliilU-lx.nii, 
Will,  I'X  , 
I- p.  rt.,  J  j" 
l.rt.,  J  i"x 


r.iiili-lii-.im,  Vli*  l"-i  '""'        liiiili  l".ii". 
Will,  J-xj;'  [Will,  I'xj 

I'p.  rt„  J  Jj'x  f  i,.(«  .iiii'lr    I'prt,  J  Jl 
I.,  rt..  3  s'Xj'  s#.inKli: 


U  rt..  3  3j' 


K  .,1  Iway.  12    Cliar. 


llinl|.|i.Miii,  >;!»  pi  I  fM.iI         HiiillliiMin, 
\V,|,,  l"v..s-  jW.l,,  I'xi 

Cp,  rt.,  J  j"».  Jj"  t  5»."'t;l^-    '  I'  'I.  -  -" 
I.,  ll  .  J  j'X  r  s»-i",i;li:  '■■  "■  -•  -l" 

liuili  liiMiii,  ^'>i*  pii  I'l'il      1  liuiiil'i.iiii, 

Wll.,  I'XJ.,'  IWlb,   I'X: 

I'p.  rt,,  J  j'X  jj"  4.-,»  .n.Klc  I  r|,.  rt.,  J  j" 
1,.  rt„  J  j'x.ii'  vi«."iKl>--    il-rt..  33") 

lillill-I.IMlM.    S.S(«   p.  1     ImmI  Hllill   llialll, 

iwi'li,  J-x;,o'  W,l.,  I'X, 

I I'p.rt, J jr^-r l•l»•'"^■.''■  '  I'- "•- -i 

jl..  ll.,  J  j.|«xj|"  vi«-i"i'li-    1..  rt„  j.i'; 

I  |liillil«,nii,'il(#  pii  ImmI  '  lliilli-licani 

IwM,,  I'/p"  \V,I.,  I'X 

I'p,  rt.,  J  -■';<  r  <»#  aiif,!.-         Ip   ll,.  J  i 

1..  rt„j  Ji'''-.i"''7*-'">'.li'  jl.,  rt,  j/; 

K,M,lway.  14'  Clear.  Roailw 


TAbLL    XIX. 

TABLR    OF    FLOOR    BEAMS. 
CLASH  A 


I  J-  (■•I,  ■■. 


Kii.iilw  .u    lb'  Ctr.ii 


Km..,Iwjv,  mcii^r,  Koj.Ujy.  joClt«r,  KoaJway,  13' Cliar.      |       Ko«away,  >4' Cltur.         iJiig'l, 


■■•  •    •-  I  •••  ■    I'x  >•'  "til,  I  X  J"*  Will,  ^  X  |o  j  Wtl),  I   X  )o 


Wd.,  l'*i'»"  \Vil.,l"»----  IWvM'x:,'  ,":».,  ,  "^'•■kM"'  i  Wtl.,rx.lo' 

I.,  rt..  i  .'x ,,'  U..nKk-  '  I..  «..  »  :•>«  .'  W  .»«l»  I..  H..  »  r  X .,'  U  a„Kk.  '■  "• '  '^  ** »  »•  •""<''•  '•  "  ■  '  -'l   '  ■■  I '  "S*  -"«"■  1  '•  "-  '  »"x .«'  7.^#  ..-ml 

llV|.'«I.  "t  IS'V>*I.  ■•  H'.S"«I.  "I 

lliilll  Nmiii,  |.'l«|ni  I liiiilllK.iii,,  I  »iiir  I.Mil  lliiill  Kmiii,  kj*  pir  I..m1  ""iI'I«.'mi.  >.:»]"<  f IIuMi.Ih.imi,  (.|J»  i«r  loot 

Wil.,  I'xjn-  I  Wth.  fx;,'  Wil.,  |"xj(,"  \V<I.,  ("xj./  Wil.,  I'x^,' 

I'l'.  Il,  -•  .•"«  Jl"  V5«>>»kIi'  l'l>-  ri.  J  -■•-  Ji'  1.5«.iiik1i-  .  I'l'.  II-.  J  -•"><  )'  ■(•  .i"»',lf  ^  ''•  "  '  '  •*"  ^i'  +  "i*  "'»•''  '  !'■  "■•  •  ■'''*.)'  '■•  ""W'*^^ 

l,.rt,  jy'x  (•  l».i"Klf  |l..rt..  JJ'x,'.,#anRW  l..rii,ajfxy.)|« ;  I    H    •  .'x  ,1' , -«  ,„:,|,  I    .1,  •  •'■-  i'6.7#»ngl. 


Illllll  In, 1111,  n;«  p.  r  f lluill.lR'.lMI, 'i|J»  \wt  lout 

Ulltlll' 

I  angl« 

W.l„rx..,  \V.I,,|-x..,'       '  ^^''"1   "^f     ,  ,       )\'I.|'VK  Wd,,l'x.,o' 

I  1.  tl     .  <"x.r  ..«  iMul,     lull     ••       •!■  n».iiiuU  l*^'''"' ^-  **  '    H««iik1'^'     I  I'  il.  ••-•'xY' S«''"kI''        I  |..  11.,  33-x  ,''(«.invlf 

I'll,! ; VxV'. .'*'    ; .',1  ;v- , ,■  ,^U_.| '■•  "■• ' ^'^^i' '••"•^"^  , ■  ■  "•; >'^ >" ^^ ■•:::'^  '  "••  '£y_r.:*j^^ 


Illllll  Ik'.iiii,  is*  1'>i  I 

\\<l.,  l"xj<"  Will,  J'x; 

U     l|..  il,  .•  j'x.'f  isW.iiii;!.  l|i,  11.,  J  j"  ■  ;J"  .i.5*>'iml^' 

I     11,.  .■  .•"  <  l"  (»  .Ihnlr  I..  11.,  i  J'X  )'  |»  .lliKl'' 

n"  V*  I.  "1  I V  i;o«I. '  1 

Huili  Ik-.iiii,  (i»  pi'i  loni  Miiililiiaiii,  ,:»  pii  (mil 

Will,  l"«.M'  Wil'.  I'x.- ,' 

U     I  |i   II.  .'  J"x.M"  V^*'"!-'.!'     I'l'.  ll. -• -•■  •  1'  («.inKli.' 

^  I,.  Il  .  -•  .■■  X  i'  |»  .iiikI,  ,  I,.  II..  }  i\'f  1'  I  |«  .iiitjlf 

'  n"  ?(>•  T,  "I  ,    ,    I 

,     ,   ,  .._        ,     .         liii  i-lii'.iiii,  ;;»|"i  l'"ii 

1.11,11 1.1,1111.  isi«  |i.T  1-..1  ; 

Will,  1">.'S'  '  ' 

,          -■      ,  .       »         1  I  I'   Il  .  .'  J  •   !'  1«  .iiikU' 

Il     I  p.  II..  -■  .•    «-•      vs».iii>;l.  I                      .       .        1 

.      ,           .        ,     «         I  I   .  -  .'!  ■   i     II*  .1  lulc 

■~i  H' Ko*  I.  "1 

tliilllln.lin.  so*  I'lf  '""' 

Will,  J'  ■<  jiV 
Il     I  p   !l.J  .-'x.'!'  ]  s«  .ihkIi' 

1  ,  Il  .  .•  .'"x  1"  .{«  ,iiij;li- 

IS"  sr*!.  "I 

r.iii!i  1.1.1111.  SI*  I ' '  i""i 


Muili  111  im  "o*  iH-r  fiiiii         Hiiill  l>iniii,  ssl*  pii  fm.'     ,  llultl U'.im,  0:«  per  fmn  riilli  luam,  6ri«  I'lr  fiiul 

'    ''      '  '  "'  '    "■-•""  Will,  I' X  JO-  Will,  |"x  p" 

Uli.ll,.  .' jfx  ,' v'(*^iiinl'  I  p.  11.,  ).fxj*7,j«aiinlf 

I,,  rt.,  J  jJ'xjJ'(,.5«aiiBU  I    II..  J3»x/7.7#anglc 


Will.  I'x.'S" 

l[>.  Il„  J  .•'■xV.i,s«.>"j;li- 

I,,  rt.,  JJi'X.r  .S».ii'Kle 


Itiiilt'lii'iiiii.  ssi*  pir  ('><>t 
Well,  J'x.n' 

I'p,  rt., -•  .•'■>  .'i'  ,|.5#.inKli' 
I..  Il ,  2  .'"x  1'  s*  angle 


lliiillln.im,  5;*  1'^''  '""' 
Will,  l"X;.i' 

l!p.ll.,  J  :"x:lV(  s«anKle 
I..  II.,  js'x.d'  s..5«  angle 


lliilliliiMin,  fi)J»  per  (mil  I'.iiili.licain,  70*  per  limi 

Will,  I'x  p'  Will,  I'x  jo" 

I'p,  ll„  :  .•'X  I'fHi.niiKlc  t  p.  rt,  .'  I'x  ii'7,;#aiinli' 

1..  rt.,  1  Jj'xy  <i,7(|laiiKlc  I..  11.,  i  i'Xf  ».)m  angle 


lluill  lii'.im,  ifi4  ptr  fiiiil        I  lliiili  liiain.  fit,>t  per  (mit         r.iilll  luam.  75#  per  fiiut 
Will,  J'xio'  ,  Will,  l"x  10'  Will,  iSj'x  vt" 


llnllllieam,  67)*  pi  1  I 

Well,  l"x  p' 

lip,  rt.,  J  i"x  )•  7. j#  angle 

L.  rt.  -•  i"  r  :-»  M<y\<- 


10' 


II' 


Illllll  111. nil,  70*  pel  (mil 
Well,  I'x  10' 

I'p.  rt  ,  i  I'x  \\"  :.:*.innle 
l„  rt„  I  I'x  rs.|»aiigle 

Ilnlll  l«ani,  75*  |«  r  (mil 
Well,  ,'„"x,„' 

I'p.rt,,.' jf  X;J''fi,s»,iii^lc 
I,,  rt,.  J  r'x.f  7,.'#  iin^'.lt 

llnilllieain,  7.S*  pir  (mil 
Well,  i^'X.id' 
I'p,  rt,,  :  ^'x  )l"(i,4»anKle 
L.  rt.,  iyx3''7.j#,inHle 


Hnlll'lieani,  S|#  per  (mil 
Well,  i',,"x  i.S" 


I'p,  rt.,  2  ^''X  •j''4.s«angle  |  Ip,  rt,.  }  J'X^J'  (1,4  angle      I  p,  ll.j  ;j''x  il")!.;*  angle  1  I'p.  rt,,  .'  i'x  ij'(i.4«  .iiigle 
I..  rt„  J  i'x  i|' 5..1«angle    ]  l„  rt.  :  fx  f  7,j#  angle        I    II.  j  fx  1' 7.:*  an^le      ]  I..  Il,,  j  .f  xj"  7,j#  .lll^le 


Huilt-lHain,  fio#  per  (mit 
Well,  J'xio" 
Ip,  rt,,  .'  -•■'X  )"  5#  angle 
I«rt,  a  .j'X  )'  5,i)»;mglc 


lliiilllii.iin,  ;iil«  |ii  1  (""I        liiiili  lieani,  fi^J*  inr  (mil 
Will.  I'x  10 


Illllll  liiain.  drj*  per  (cmt  I  uiltliiani,  76J#  per  (mil 

Well,  t'x  )o"  \\il',  r'd'x.-iS' 

Tp.  rt,  2  ;»'x  1' 7,:#anKle  I  ji  rt,.  j  jj'x  .•j'(i,s»angle 

I.,  fl.,  J  3'x  3"  7.7#  angle  I    rt,,  1  j'X  j"  7.j#  angle 

Illllll  lieani.  70*  per  (mil  Hnilllieani.  78*  per  diot 

Wei),  J"x  p'  Will,  yx  J,' 


:"    :: '  :  wiii,  i- ><...,■  wu.,  i"x,o'  weh.  j-xp-  w.i,,  ,',,''Xi(. 

,     ''; '    '^^    ,    .        ,        'ip,  rt,  .■-•■-.M' 4,s»  angle    I'p,  rt„  2  .')'x.,- 5,5*  angle  ;  I'p.  (I.,  j  fx  ,J' 7,7*  ,,ngl.    I  ;.,  H„  2  2-x  il*  (,,.|»  .nigle 
'       '"l    '  "'  r  *  '•   '  ^""'  I.,  rt,,  2  2-x  ij-  5,j»  angle      I,,  rt.,  2  jj-x-l'  <^-5«  a"Kl«-'  !  !-•  «■.  :  ,f><  .i"  !<t»  •ingle       I..  lU  2  j'xj"  7.2#  anslc 


is'  so*  I,  iir 

Illllll  111, nil,  S-'*  per  I'll. I 
W.  I..  \"-<  :('r 
,li-    Ip,  rt  .  2  2''x  !'4«.ingle 
1.,  Il  .  -•  .'Tx  i'  II*  .ingle 

I  llllill  li.-.iiii.  S'l*  l"f  fi»>' 
W,l..  i'x:;' 
i  I  p,  ll„  2  2"^  r  .|»  .ingle 
'''  il..  rt.,  1  3j'X.)"4.4».1liglc 


'  lliiilllie.iin.  ;,S«  per  lo"l  |:iiilr-lie.nn.  ("is*  |)er  (mil 


I  Well,  I'x  V 


Will,  I'X  50' 


I  I'.iiill-lii.iiii.  Sli«  per  (■"'1 
1  Well,  J-X27'' 


<li- 


.1  I'p,  rt„  2  2j"x  ^"  4,4*  angle    I'p,  rt,  2  21' m'  s.;*  angle 


I.,  rt,,  1  J'Xj"  5*  .mgle 


I'p.  rt„2  i"^:\'  4, s«  angle     I'p.  rt.,  2  2'x  3I' fi,)*  angle 
I.,  rt.,  2  2'x  ;!'  s,.i#  angle       1.,  rt„  2  i'x  /  7,2*  angle 

Hnililie.im.  i'>#  per  (out  liuilt-lieain,  f/ij*  per  (nut 

Well,  r'^.P'  '  ^^''''''  rx,3"' 

I'p.  rt.,  2  2  '  X  )"  5*  angle  Lp,  rt.,  2  21''  X  j'  r..7»  .ingle 

l„  «..  s  3'X  j"  5.i>»  angle  i  I,,  fl.,  3  j'XjJ*  7.7*  angle 

_         _  1 

linill.lie.ini.  ii;«  per  (""I  Hiiill-lieani,  (*)»  jier  (not 

Well,  J''*<r'"  Will.  |"X  p' 

I'p,  rt  .  2  .rx^"  7.2*  .ingle 
I,.  11.,  J  j"Xj"8.4#aiigle 


lliilll-lieain.  75*  per  (mil  IIiiilt-lH'ani,  .Sl«  per  (mit 

Well,  I'/X  Vt"  Well,  rj'XlS' 

I'p.rt,,  2  2f  X2i|'(i,.s«angl.  I'p.  rt..  2  2"x  ,l'ri,4*angle 

I.,  rt,.  2  J'X)' 7,2*  angle  l„  rt,,  2  .fx  )"  7,2*  angle 


Ilnlll  III ,1111,  ,s.'i«  p<  r  Imii 
Well,  ,'',,"xj,S'' 
I'p.  H„  2  2rX3''fi,7#angle 
I  ■  11,,  2  r'<.ir77#a"Klc 

I'liilt-lii  ,1111,  .S(i*  per  (mil 
Well,  ,'„"x>S' 
I'p,  rt..  2  j'x  55"  7,7«.iiigli 
I..  fl.,^3'XJ"S..(*angle 


'3 


L.  rt.,i2j''x2|'6.5#  angle 


I'.ullt.lie.inl,  SSl*  I'll  I'l"'         liniltlieani,  !.;(*  per  (i"'l 
Will,  I'v.-'S"'  :  Well,  1-x,,'' 

I'p.  rt.,  2  j'xjJVi  s«  .niglf     '  I',  tl,  2  j'x  -,'(*. ingle 
I..  II.,  2  2''x  i' 's#.iiigle  III,-'  'l'-  ;"  ii:#.ingle 

i 
Unlit  lieani,  s''!«  per  (nut         llnilt'-lie.iiii.  i.s»  pir  (mil 
Well,  l"x  i< 


lliilll-lieain.  70*  per  fnnl 
Well.  I'X  p" 

rp,  II.,  2  I'x  jl";  7#  angle 
1,.  rt..  2  fx  i"  S.,|»  angle 


Uniltlieam.  764*  jwr  d 

Will,  fi/X,;" 

l'p,rt„2  2rx2j'ri,s«  '■    III  l'p.rt„  2  2i"x  5' (-.,:«  angle 

I,.  rt„  2  3'X3"  7.2#aii.;i.       I  I,,  fl.,  3  3'X3l''  7.7*  angle 


Ilulltlicam,  82l#  per  (mil 
Well, />,'x.,S' 


llnllllie.ini.  7.S#  per  I I  llnlll-lieani,  S(i#  per  (""l 

Will.  t'',."'<,V'"  Well.  ,»,,''X3.S' 

I'll,  rt,,  2  2'xj|'(i..|*,ii'. 'i|  lp,  rt„  2  3'x  !j'  7.7#angk 

l„  rt„  2  3'X3'  7,2*  ,111.;!'         I,,  rt,,  2  3'X  j'  S,.|«  .angle 


Illllll  lieani,  75*  per  (not 
Well,  ,''fl"X  vi" 


Itulll-lieani.  7oi#  per  t' ■  ' 
Well.  ^,-X;7' 
l■||,  rt„  2  2-x  5|"l,.,,«.llil 

I.,  rt.,  2  3'X  )'  7.2«.iiH'.K 

Ilnlll  beam,  ,S2l#  per  (i"ii 
Well,  ^/XiS- 


I'liilllieam,  S<)#  per  fnnt 
i  Well,  ,■',.,  "xj.S' 
I'p,  rt,.  2  3''X3"8,.|«  angle 
l„  rt..  2  .j"'*.!!'  y*  '""git' 

llnilt-lieam,  i)I#  per  (mil 

Well,  r'./x.vS' 

I'p.  rt,  2,V'x  ,i"iri»,iii^k 

1„  rt,,  2   i"x  ("  ii.7»  ;iiinle 

IllllltlnMni,  I).)*  pel  l""l 
Well.  ,'..,' X3S'' 
lp,  II.,  2  3'X4''i),7«,in(',l. 
1„  rt,,  2  3°X3J''  io,.|*  aiiiji 


Hiiilt  Kani.  .Sf)»  per  fimt 
Well.  ,VX;S- 
Ip.  11,.  2  3  ■  X  !'' ,S,4«  angle 
I,,  rt.,  2  3"X3l"  y#  angle 


Uniltlieam,  91*  per  (out 
Well,  i-'.-XiS- 


VV,  I,    I "  X  2.,'  W.li,  l" X  ,„ '  Well,  ,',  •  X  ,4'  Well,  f,x  3V  j  ^^ eii,  ,-,  •  X 3h • 

I'p   II     •  •'X2i''  i,5#,ingle    rp,rt..2  J'-  ■,l'l..4#aiigle|rp,rt„22f  X2i''(..s«angle;rp.rt„22j"X3'(i,7*,i.Kle,l'p,il,.23'X3j''i,«.ingle 

I    rt     '•  •'X3l'  5,3*  angle       I..  II.  2  I'x  ;' 7  2#  angle       I  I..  rt„  2  3' X  3- 7,2*  angle         1..  rt.,  2  3'X3j' 7,7«  angle     ,  1,.  rt.  2  3'x  4"  i,,;*  angle 


Hullt  lieani,  i>S»  per  font 
W'll'.  ,•■„■  X3S" 
l'li,ll.,2  )''x,-,!'ii-.l»  angle 
I.,  rt.,  2  i"x  jj"  1 1,7*  angle 


llnilllieain,  ioi#  per  (out 
Well,  iV.'XjS' 
I'p,  ll .  2  3"X4''  11,2*  aiii;U 
1„  rt,,  2  3''X4'  1 2.7*  .mgle 


lliiill-liiMin,  S^i*  I"  I  I' 
Well.  I'x, 


I'.iiill  I'l.iiii. '-,'  =  pii  (""I      I  liiiill  lie.iin.  7(il#  pii  ("I'l      I  Ilnlll  lieain,  Ss*  1 

' ""■-•■'  W'lli, /i,,,"X3S''  1  Well,  ,'.,'X3S"  |  Weli.  , 


W'.l.,  i">  31  ■ 


Well.  iV,"X,s' 


■am,  Ss*  per  l.'.l  Hnllllu  am,  f)4«  per  f'loi        !  Ilnlll  liiani,  I0|»  pel  l.i"l 

-       ■""  Well.  ,'.,'X3S"  W'eli.  ,^,.,"X3,S' 

I'p,  rt..  2  3"x  4' .i.7«  angle    I  I'p.  rt..  2  3l"x  |"  u-S.nv.le 


Well    1"^  '"  \\ili,  1    >  ;i.  wen.  J-,;    A  i^  ..ll.,  f,,,    ^.ji  .  I.,    -.r-  I.. 

I',,  li     ■  -r  <  •(-  I  -«  .nigli    II'-  Il .  -  -•'.■  ■   ;■•  (■-*  ■"'kI^'  I  I'P-  "••  -  -i'x  2i''(..5»angle  I  I'p.  rt..  2  ^'x^'  72*  .iii..!.       I'p,  rt..  2  3-x  4'  .,.7«  angle      I'p.  rt..  2  3S-X  , '  1  2«  .in,le 
I.  ll„  2"2l"X2|''  SI*  ...i^'l"-'  ;  1-  rt,.  2  3";  .[.    7  7«.'»>!l^'    1  I"  II"  -■  -i'x.r  7-2#  angle      j  I..  11.,  2  3"X3'' 8.4*  angli         I.  rt„  2  3'X3i'  to.,,*  angle    I.,  rt„  2  3i   X4'  I3.'*.n'gle 


I  liiiil,  111  „„  <i>l«  „. ,  l""t      '  lliiill-lieani,  1  -■=  p.  r  L-.l      :  H l-eam,  7S#  pel  (uol        '  llnill-lie.ini,  SC*  per  (""i  nnlli-lieam,  .>S#  per  foot  lluill-lieam.  ICX*  per  ("..1 

'     '  Wili.l-. ,-,..'■  W'll,  ,V"x,„"  iWili,  ,"„-X3S'  !  Will,  ,'■.,•  x,S"  {Well.  ,V''X3S" 

x  ;i'r,..,#aiii'.le;  Tp.  rt.  2  ,\~'-}\'  ;  ;3  •'!'.■'•  ;  lp,  rt..  2  3''X3.rio..|#anjL  j  Tp.  :!..  2  4j"- .f  I2.ii».i 


W.  Il,  I"/  p" 
I' 


n,   ,1     ■  •"'  i-|*.ingl.-         1  I'.  H.  2  i"-  r  ;■-!»  •"'>;l^      Iprt.  2  2-X3i',V.,#,i,iKle;  rp.  rt..2  3-X3i- ;  ;=  ■'i'.>  j  1  p.n..2  3-x.!i    io.|«:anj,le  ;  l  p.  :..  2  4    "4    .2.i,*.,i.K.e 
1,  ,|.,V4"'X3'(,.7#.ingle    jl.,rt,2  rxr::#..ngl«^         I  .  rt.  2  i'x  3"  7 -•#  ..ngle       :l..rt.,2  v'x  3- S..,»  ..m;Ie      ,  I..  11,.  2  3'x  3i-  u,7#  ..ngle  |  1„  rt„  2  3i   '<  4    i.V'.#;.ugle 


14 


'5' 


18' 


22' 


23 


24 


K.-ailway.  M' Clear,       '        Roailwav    if.' Cle  .r.  K.niilwav,  i8' Clear  Roailway,  ao' Clear  Koailway.  22' Clear, 


Koailway.  24'  Clear.  ,';,'";„, 


»1. 


\ 


•«Si> 


■■-^ .  m 


^^fflj'w 


% 


\ 


i 


w 


Pail.  1 


Koailway.  12   Clear. 


,!■>«  I 


u,    yM\ 


lo'  ,;o#  I 


^o\■  y\*\ 


l:iiilt  hum,  iSia  |n-r  I'.int 
Wil.,  l"x  t 


Roailway,  14'  Clear. 


ioJ",iil#I 


Kuailwa 


IJ".|J#I,., 
Ituilt-lic.nti, 
Will,  l"xi, 
Up.  II.,  I  2" 

I.,  n.,  -•  c"x 


18' 


■9 


1::"  .l-'*!,  iir  I  ;'.(:#  I.' 

Iluillln'.im,  jSJ*  per  fool        lluilllH.iin, 
Well,  J'Xi.S"  ;  \Vil>,  1'  X:, 

I'p.  11.,  2  .:"x:!>'  ;,.5*  •'"«!'■ '  I'l'-  ''•■  -  -" 
I..  11..  2  j"xj.i";,.s#.in);le       I- ll., -•  .-"x 

ij'.i:#I,  or  ;i3".So»I' 

li\iilll>eai\i,  viS*  l"r  f""'      i  liiiill-'"-!"'. 
\Vcl>,  J'xiS"  '  :  Well,  I'xj 

Cp.  fl,  .-  j'x.'l'  v.S«.iiinle    I  p.  11.,  -•  i" 
I.,  rl,,  .•  .-"x  ;■'  |#  .mule  .  I.,  ll.,  J  2")< 

!-•' .|j#i.  .11  ij";;"*!.! 

liuilllu-.iin,  .|i*  pel  f""l        I  lUiiU-Ueain, 
Wei.,  rxh,"  IWel..  I'x: 

fp.  ll.,  2  yx.'i"  _^.5#an(;le    Tp.  ll.,  J  2" 
I.,  tl.,  -'  yx;,''  ,)#  allele         .  1,.  il„  .'  :'> 

i.'".ir#I,  ..1  lV'.^o»I. 

lUiill  l.eani,  i-'l*  per  f....t        lliiilll..  am, 
I  Wei.,  !"<  -o    '  i  Web,  V'x: 

|..ll,  .-  .'"X  _-r  •,.^«.inule   '  Tp,  ll.,  -■  --"x  i\'  ;.5#  ai.};le     I'p.  ll.,  -■  :' 
1  .  ll ,  2  '"x  -y  v>»  an.ule       I.,  ll ,  J  :"x  ;■'  I*  ■>"(;>>■■  i  l-  I'-.  •:  2") 

ir  .i.'«I.  ..1  ,ii"5o»I,  ..r  j' 5"  .10*1. 

Piiili-beam.  3Sl«  pi  1  l.n.i        Huili-he.im,  .|:1«  p.r  f.i.>t        liuilllie.ini 
Uel.,  fXis"  i  Wei.,  }"x  JO"  IWel.,  l"x. 

Ip.  ll.,  •  .'"x.-r  .v;«anule    Tp  ll,.  •  .-"x.'r  v^*•l",l;le    Tp.  ll..  :  .' 
I      1!  .    '  J    X  iV  \\1t  .^ll^;le        I.,  ll,  2  .-'x  '/  .(*  allele  :  I.,  ll.,  J  .' '  ^ 

1,-     |;3  I,  ..1  1^"  :;o»I,  ..r  [15' 50*1. 

Pmlt-l.eain,  vi!*  per  f""l  M.i.ii-I.e.im,  .( |*  p.  1  f'.'.t  liiiill  lie.im 

Well,  )"x,S-  W.I.,  I'xji"  ,\Vel.,  1"X 

Ip.  tl.,  z  j'x  'i'  v>«-'"e.l''  l"l''  'I.  -  2"x;i\v.;*.»i'Kl>-'    I'P-  "••  -  - 

1,-  ll.,  :  2"x  ;'  .|«.ii,Mle  I.,  ll.,  2  2"x^"4#  allele  ,  I.,  ll..  -•  sj" 

I .'"  .(2*  I.  ..r  1  S"  .^o*  I,  ..I  !  I  .V  50*  X 

lli.ill-lie.im,  V)**  per  f.".l        Huiltl..  am,  .(5*  pel  f.".!  liuiU  l.eani 

Wei.,  l-><'^"  '  Well,  I'x  3-"  W.I.,  I'x 

,  Tp.  ll , .'  j"x  :Y  ;.;»  .iiiBle    I'l'.  ll.,  2  -•■x  .-r  vi*  -'"Kle    Ip-  ll .  •!  ^ 

I  I.,  ll.,  -•  i'x  j'  4#,lllKk-  j  I.,  fl..  2  I'XJ-  .)«  ailKle  I  1..  tl..  2  2" 

"i2'42»I,..r  |l.S'.5o#i,..r                            |  l!„i|,.l,..am 

:  P..iili-|.e.im.  .|i#  pel  fo.,i  liiuli-I.e.uii,  ,|i«  I'er  I. ...I        |  ^^.^^^ 

Wei.,  r  XI,,-  Well,  r  >■-■.'                               !(■      ,1     ,  , 

fp.  ll,  2  2"X2r.!.;«.m^;l.  fp.  II.  2  2-x,r  .v;*--"'.''.!'-    ,',,    ',  ,. 

1..  ll,  2  -•"  X  ',■  .|»  .uiKle  ,  1-  ll-.  -•  •:'■''  1"  t*  -"'K'e-          ,    ''__'" 

I  ,-  ,  .a  T  ..r  ll"  SO*  I.  "f  i>  •..  1 

I-    4--*  !■  ■"  [J    '      ■»■'  1  lluill-lieaii 

i  liiiill-ln.im,  42i«  per  f....l        llmlt-lie.ini,  4.*  j.er  f....l  ^^.^^^    ...^ 

:  Wei.,   i"  '  --O-  Wei..    I'x  2^  ,.         '',, 

1  l-p.  ll,  2  2-x  2r  15«  .ii.Kle  ^  l-p.  ll ,  2_2'x  2i\?.5*  »"«le    ,  '^j  _  '  ", 


I.,  ll,  2  2"x  ;,•  .t#.mKle 
I  15"  V,»I,  ..r 


I.,  ll,  •  I'y-  \''  4#annle 
I  \'  V*  J,  < 


lUiitl-hean 


Uiiili-I.e.ini,  n«  per  f""t  llmll-l.e ,1111,  soJ»  per  I....1      \^^^^   y^ 

Wei.,  r^-i'  Web,  I'X^f'"  I-,,  ,1     , 

l-l..  ll,  2  2-X21-  v;«ani.le    I'p.  ll,  2  2'x  2i"  1^«  aM,-le       1.     ;;; 


p.  I 
1..  ll. 


;■  |#  aiiKle  I.-  tl-.  -'  -'  *  )"  4*  •'iik1>; 


I.,  ll,  2  2' 


iVv-»I.  "1  ^,0;,.«I,  ..1  'ituili-K-aii 

llmli-lnam,  4;*  per  l""l  Hmll-li.  .1111.  ';2»  per  I....I  ^^.^^^ 

Wei..  T"--'  iWel..  rx24'  I-,,  t'l     - 

fp.  ll.,2  2'X2r  •,.5»aiH',le    l-p.  ll.  22"  xjj' 4- S#.->iH',le        ''     ■/, 


I.,  tl ,  2  I'f-s'  4»  allele 


is"  v.#I.  ..r    - 

limit  l.eaiii,  -tC*  per  fmil 

Wei.,  i'x  2i- 


I.,  ll..  2  2''x  ',!"  .;■•,« -1";  

Hiiilt-lieam.  i;2l#  per  (....I  lliiill-i.e.ii 

Wei.,  l"X2s'  Wei.,!"" 

Tp.  II,  2  2''x2r4  >#-iiii'ie  rp.ti.,  2 . 


I      tl,  2   2-X    (M#.">M.l'-  ['•■"•--  .1      -i  ^ 

|>"V«I.'"  I  |l,iiltl.i-.iiii,  q;»  i'er  I....I  limit  l.eai 

P„„lll»..m.  p-i»pei  (....1       ,^^.,,,   J..,  „,.  W.l.,  r> 

Wel.,rx-r  ,       ri..  tl,  •  2"X2r  I  sSaiiKle  rp   11,2 

r,,.il,2  2    «2l     ;s«...el.     I     „,,..x,J',.,«.,„j;le  1.11.2  J 


I,  tl. 


-■"-   !"    I#- 


I'.in.l 


IS'  i'l*!. '•'  |l„illl.>-am.  SI*)..  1  l-.l  I'.uill-lH'il' 

I'-eil  1"  ■ I  '*  I"  '    '  ■    '  Well,  i"X  27*  \V  el..  I": 

^^'' ''■*""'''  ,.     »      1    i-p.ii...'-'-x-l-|-^*'"H'i'  I'P  "■•J 

I  |,   ll,2  2"x:l"  !.s«  mul.-    I  1^1     .-.-x  il-  s,t«  in,.,l.  I..ll,22 
I.,  ll,  2  2"x  i"  4«anKli          1 

Kna.lway.  1  a   CI   ar 


K.M  lw.iv,  14    CI.  .11 


Koal 


TABLE   XX, 


TABLE    OF    FLOOR    BEAMS. 

CLASS   B 


Roailway.  M'  CU'ar.  Koaitw.iy,  lO'  Clear.  Roailway,  i8'  Clear.  Roailway,  20'  Clear.  KuaJway,  22'  Clear. 


Roadway,  24' Clear.       i,''^"^! 
'      ^  Length. 


loj-  ill*  I 


|J".|.'#I,  i>r 
l(uill-l)c.ini,  3SJ#  per  font 
Wth,  J'X  iS- 

I'p.  II.,;  j"x.vi';,.f;*  •'»«'>-■ 
I..  Il,  .'  j'>  -vl"  .'vS*  •!"«''■ 


1J".(.'#I,  nr 
llnill.|ic.\iM,  .|i,J#  |ii-r  fniii 
Weh,  l"xi,|'  ' 
Ip.  11.,  :  :    '  :l",v.S*.>iit;li- 
I..  11.,  J  _•   X  ;"  .|#.iMv.le 

i;'.,:#I,„r 
Huill.lii.itn,  \},\^  per  fiiDt 
Well,  \"  X  .-o" 

I'p.  11.,  J  :"x  jI"  v5*  •'|'k1<.' 
I.,  ll.,  .!  .'"  X  j"  4#  .-iiikIc 

|J".|:#I.  or  I  15"  50*  I  "f 

lliiilllieain,  Vll*  I'l'  l'"ol       ;  liuiltlie.lm.  15#  per  f.i.il 
Well,  J"x  |S"  !  Will,  1">  .-i" 

Ip.  ll ,  -•  -•"><  -'l'  v.i*-i"Kl^'    I'l'-  ll'  -  -■    <  -1"  .Vli*  '""K'^' 
1..  ll,.  -•  -•"  x  ,\"  |»  .ui.nle  1  I.,  ll.,  .:  -•   X  ;"  .)#  angle 

1:"  .|j»I,  ..1  ;i3"5"*I."r 

lliiill  he.iiii,  .(i«  per  f.M>t        :  lUiilllieain,  .|ii#  per  fciul 

Wei.,  yy.  M'  :  Wei.,  |"x:y' 

I'p.  ll., -•  '"x.-r  3. ;«  angle    l]..  ll.,  :  y  x:r'  j.;*  aiigk 
1.,  ll.,  1  ::"x  ;■'  .)#  angle         .  !..  ll.,  -•  : '  ■  i"  I*  -'"K't' 

IJ".!-'*!,  MI  '  15"  50#I,  "r 

linill  beam,  i-'lS  per  foot      '  Hnil|.|ieain,  .(:S#  I'er  (o.it 
Wei.,  l"X.-o    '  I  Web,  |"x  j;" 

.;lo  '  I'p.  ll.,  -■  :!"x  zV  i.5»  angle    V\:  ll.,  -•  :'  x  zV  'vSWangli 
le    jl,.  ll,  .' n'x;- .(». ingle  |  I.,  ll, -•  ;"  x  ;' 4#juigle 

1 15' 50*1,  •■!  1 1 5"  50*  !•  "I- 

il       '  Unill.heani,  .|.'1«  pir  Inol       |  ItnillI.e.iMi,  |.)«  per  f.iol 

!  Weh,  J"x:c-  i  Wei.,  fx,;" 

igle    fp  ll..  -■  j"x.-r  ;  ;«.inule    I'p.  ll.,  -'  .• "  x  :  J "  j.  5*  •''»«1'^ 
Ir       1.  ll.  .:  j"x  ,"  1*  angle  :  1..  ll.,  J -• '  x  t' 4*  angle 

1^"  v.»I,  or  I  r.i'  :;o»I,  or 

,1  l;ii;il-lie.lnl,  .(,|«  p.  r  font  lUlill  lie.iin,  ;ii#perfo.il 

\V,I.,  i'X.-l"  ,  Wei.,  i'X.M,' 

,glr    I'p.  ll.,  J  ::'x.'J"  v;*.rngle    I'p.  II..  ^  .' '  x  •,'  .i#  angle 

I.,  ll,  r  2"  X  ;,'.(«  angle         ,  I.,  ll.,  .:  jT  <  ;"  |..l*  angle 

I  ;"  \ot\.  Ml  !  15"  50*1,  Ml 

.1        liiiili  l>.  am,  -i^*  per  I'mmI  llnill  l.eain,  ;i !«  pi  r  ImmI 

.Well,  J-X2:"'  Wei.,  I'x-;- 

igle    I'p.  n.,  :  :'x  .'!'  ,vi*  ■'"Kle    t'l'.  ll .  .:  '-"  <  -T  \->*  ••>"«l'-' 

I.,  tl..  2  3"x  ?"  !«  .ingle        ,  I.,  ll.,  -'  ;">  ;'  5*  •■•"kI'-' 

l.S'  50*  L  '"■  j  Hiiiliheam,  ;-'l#  I'cr  f.iMi 

1        I  lUnlt.lie.un,  .)(*  per  lui.l        |  ...  .,,   i"x  ••!.'' 
...  1.    1  ,•  ^.  .  >*  I  '  ^ 


15"  50*1,  iir 
lliiilt.lii'.ini,  .i'.#  per  fmit 
Wei.,  l"x  j:" 
I'p.  II.,  J  i'^i\'  .).5#angl 
1..  ll.,  .'  j"x  j"  |#  angle 

15"  ifM  I,  (.r 

r.itill  luMin,  .(S.l*  per  I'omI 

Wei.,  I   x.-.|"  ' 


.,  .,   ,               1.,.         ,     .     i  I'inll  lieani,  ?.(#  per  fmit 
r.uilM.eain,  5ol#  per  flint       ,,.  ,    ,, , 

Well,  V'XJd' 


Well,  J'X27" 


,.      ,  ■       ,       ,,       ^        ,     '  !'■  II..  2  .I'X  l"  .».i#  angle 
L'p.ll.,.yx..4'j.s#..ng|.     ,     „.,...l'x,"5Vangle 
I..  II.,  .'  2" X  5"., Wangle  \      S    ^*      h 

15"  50*  I,  or 

l:nill.l.ea,n,  s\\*  l>^r  f....t  '  l''"l'-'«^»n<.  55l#  1'"  foot 

Weli,J"x..,«  Weli,i'x../ 


Iliiill-licain,  5.SJ#  per  foot 
Well,  }"x  30" 

Up.  fl.,  ::  2"X25"4,5#aiiglc 
I..  H.,  2  2"X3j"  5.3#  angle 


Huilt-lieam,  62#  per  foot 

Well,  J' X  30' 


lp.ll.,.-y'x:i"  5;#.nngle    I'p.  ll.,  .  ."x  -i'+S*  angle   '  I'- H- =  ='X:i"  4.;#  angle    Vp.ll.,.  ^J'x  j'5-5#-->ngle 


11' 


I.,  ll.,  J  J'  X  3 "  ;|#'.u.gle         I  I..  II.,  .'  zV  X  3"  5#  angle_  '    "'•  -  -i  "^  3°  5#  angle 

15'  50*  T,  or  I 

llniUlie.mi,  ;ol#  ii.'t  fuol      1  ''"i"''".'-"".  54j#  pcr  foot  |;,nli.bcain,  57#  per  foot 

Well,  r'x.O'"  iWel,,l-x:!7'  \V,h,}'X3o' 

I'M    11      .   ."x-r  •c«inele"-'l'''l"""''=l    ■'■■'5*^"'^''  I  >.  ll.,  3  =' X  .;r  4.^^  .angle 

1.'h.!;  ;  "xr  i*;n*o  '     i  '■■  "'•  =  =rxyjW^  l  .  .l..--^'X3i-,3*.angle 

l:'nil|.l!.nm,"si  !#  per  foot      |  ""il'-l'^'a"'.  5Si#  1'"  foot  i;,i,l,.l,ean,,  Tx*  per  foot 

Wel,,i"xr4'''  Wcli,rx=S"  U>l,,  i-X3o" 

l-p.  11.,  3  3'X:r.,.5#angle^'l''""  -  ""''-i    -fS*  angU  I  ,.  il.,  :  2-X3'  ;#  .-.ngle 

I.,  tl,  2  2j"X3"  ;#angle       j  '-  ""  ^  =i">^3''  5#  a»Kle  I    ll ,  i^'^i'  5.9#  angle 


I,  ll.,  2  2}"X2}"6.5#.inglc 


IJuilt-lK'ain,  63j#  per  foot 
Well,  }"X30'' 
Up.  tl.,  2  2"X3"  6#  angle 
1..  n.,  2  2j"X3"6.7#angle 


1 
Huilt-licani,  ri5#  per  foot  i 
Web,  J'X3o" 

L'p.  ll..  23' X3»fi.5#  angle    ! 
L.  fl.,  2  3"X3"  7.2#angle 


13' 


lUlillbe.iln,  5:1#  pel  f.M.I      ;  lluill.beain,  57*  per  foot        ,  r.iiilt-lieani,  62#  per  foot  llnill  beam.  (r\%  per  foot 

Web,  1"X25'  Well,  j"X2i)'  W.b,  J'xio"  Web,  i'Xjo" 

I'p.  ll.,  2  2"X2J'  4, 5»  angle  •  I'p.  ll.,  ;  2"x  :J'  4.5*  angl«    IV  il ,  2  2i''X3'  5.5#  angle 
I,,  tl,  2  2i"X3'  5«  angle       '  I.,  fl.,  2  2"X3l'  5.3*  angle      I    ll.,  2  2}"X23"  6.5#  angle 


*>  I  o,  J    ^  iu 

L'p.  ll,,  2  3"X  3"  7.2#  angle    I 

1..  fl.,  2  3'X3J"  7.7#angle    I 


'4 


ISuiltbeam,  vij*  l"^r  foot      j  llnill  beam,  59#  per  foot  buill-lieam,  (,},\*  |icr  foot  HniH-lieam,  70*  per  foot 

Well,  i"x:i,'                          i  Web,  )-'X;o'  Wib,  i-X3o''  Web,  ("Xjo*                                     , 

l'p.  fl.,  2  2'X2l"4.;#anglc!L'p.fl.,  2  2r'X2r.t.9#angl.  i  ].  fl.,  2  2'X  3"  1*  .angle  ^V'^-  -  .'i'x  34"  7--#  angle 

1..  II,  2  2j"X3'5#.ingle       1  I,,  fl.,  2  2-X3i"  5.3*  an;,  -  I    il.,  2  2j"X3' i'.7#  angle  j  I- fl- 2  3"x  3"  S.4#  .angle      | 

liuilt-beam,  75*  per  foot 

..en,  *    'v ->J                                         ..en,  4    '^  ^                                        ,.  .  i.,  ^     "  .>"  .»eij,  j-j    ^3'* 

l'p.  ll,  2  2"X  24' 4.5*  angle    l'p.  fl.,  2  2'X3'  5*  angle  Ip.  fl.,  2  3"X  3"  b.s*  angle  l'p.  fl.,  2  2fx  2j"(i.5#  .lngle 
l..  fl.,  2  2l'X3' 5#  angle         1..  fl.,  2  3"X3"  5.9#anglc  I    fl.,  2  3"X3"  7.2#  angle 

I'.uili  beam,  "#  per  foot        1  linilt-beani,  b2#  per  foot  '  liailt-lieam,  70*  per  foot 

Well,  I"  X  2./'  ;  Web,  J"  X  30'  Web,  J'  X  30' 


llnill-beam,  555*  per  fooi       lluilt-beani,  6o#  per  foot         liuilt-beam,  CjJ*  per  foot 
Web,  \' X  2.S'  Web,  J"  X  30"  W  >b,  \ ' X  30' 

..  »...,»  ...  1         ,,        .t       __«,..»-*. 1.  1..     .1       .    .n  ^  ,»  ,■   .^^ 1.. 


lUiilt-lieani,  76J#  per  foot      | 
Well,  IX2.;'  i  Wei),  J    X30  "en,  t   ^3"  ^^  il'.  T'.!"x  35"  j^, 

l'p.  fl„  2  2rx  2I'  4.<)#  angle'  l'p.  fl.,  2  2J-X  3'  i;.5#  angle  l'p.  ll,  2  3'X3i"  7.7*  angle    L'p.fl.,2  2j"x  2:i"6.5*angle 
I..  fl.,  2  2r'x  21"  5.,)*  angle  I  I,,  fl.,  2  2}'x  2}' (i.5#  angle   L.  I,  2  3"X3'S.4#angle      ,  L.  fl.,  2  3''X3' 7.2^  .mgle      . 


Uiili.beam,  s^*  per  fool        j  llnili-bcam,  (n,\*  per  fo,  1     :  l;nilt.lie.am,  75*  per  foot  liuillbcam,  78*  per  foot 

Web.  J"x,o'  iWeb,  J'Xio"  Web,  |»j'X34''  |  Web,  ,■•,'■  x  36' 


'  .•..".-■■' i-r  I  Web    J    X'!,'  Wei.,  J    X',o  j  W  el.,  J    X.  ;o  "en,   fj    -v  j4  |    ■■>■■.  m    ".v 

hVeb,  \-S2i'  1^.      •     ,  ,->,,,.^.5#a„(,U  l-p.tl,2  2rx:r'4..»#angle  l'p,  fl..  2  2"X5"r*an  i.  i  I'p.fl.,  2  2;'x  2rf..5#  angle  :  Up.  «..  2  2i"x  2^' ('..sSangle 

„g|..    l'p,  fl.2  2"x.-r3,5«angle    ,    ^^    ,  ,-x  a'"  =.,#  angle  |  I.,  fl.,  2  2rx  2^  5.4*  angle  |l,.  fl.,  2  2.4' X  3"  f,.7#  ..n..  I  .  ll,  2  3-x  3- 7,.*  angle         I.,  fl.,  2  3' x  3- 7.2#  angle 

j  I,,  fl.,  2  2"x  i"  4#,ingle  _  !  '  -  - 


lit 
ngic 


15"  i;o#  I,  or  j  |.,||||.|„..|,„^  ^,|#  |„,|-  f,„,|      !  II, lilt, beam,  (o*  pel  foot        '  llnill-beam,  b;*  per  1. 

linill-beam.  .p#  |ier  foot  ^^.^^^^  ^.^       .  -  j  ^y^.,^^  j.^  ,,,.  ^y^.,,^  l"X3o" 

^^'•■'''  rx25'  |.  ,'|  ,  ."y,l'4.5#angleiUp.  fl,2  '''x  ij'  i;.,*  angle  l'p.  ll,  2  2'X  3!- (.,.1*  ,1 
Up.  II,  2  2'x2l  3-5*»"*;l^' ,  I..  „.,  ,  ,»x  if' 5.5«  angle  |  I,,  fl.,  2  f '^  i"  .s..;#  .mgle  .  I,,  fl.,  2  3"X3'  7-»->"- 
L  fl.,  2  2"X3' 4»angle  -'  | 


IJuilt-beam,  76i#  per  foot 
Weh,  ft" X  35' 


Hiiilt-beam,  ,Si#  per  foot 
Weli,ft'X3,S' 


Up.fl.,2  2J"'x2f"fi.5#aiigle;Up.rt.,2  2f  X2j"fi.5«angle 
I.,  tl,  2  fxy  7.2«  angle      I  L.  fl.,  2  3''X3"  7.2#  angle 


18' 


■  9 


I5'50#l.o,  i;„i;i.beain    i;;«p.ifoot        '  llnilt.be.un,  fii  i#  |..  1  fool      !  llmlllieam,  fi7j»  p.  1  i. 

t        I  llnill-beam,  sol*  per  lo.il        „•.,!,    i-yvS  i  Web,  ("x  ,0'  Web,  I'Xjo- 

Web,  J'X2(."  "       ' 


Web,  J'X2l."  ,.|,  ij^  ,  ,;v,jv,.5#.,„^ii.lrp,fl„22l''X5'  .;.i;#.ingle:i'p.fl„22rx3-::» 

ngle    Up.  ri„  2  2'x  2i'  3,-,*  angle    ^         ^  __,^      ,     ^        |^,      ^    „  _  ,  ,.^^j.  f,^^  _^,,j,|^,    |  ,    „^  _,  ^-^  3!'  7.7s  .. 

I..  11.2  2"  x;    4*  angle  '^ 


llnill-beam,  7S#  per  fool        |  Ituill-be.am.  Si;*  per  foot 

Web,  ft' X  3(1"  !  Web,  ft'X3,S- 

I'p.  ll,  2  2'X3l"  fi.4#  angle  ,  Up.  ll,  2  \"-<f  7. 2#  angle 


1  ,  fl.,  2  ;,"y  },"  7.2#  angle 


IS"  v.»I.oi 

ltuilt-b(  am,  i;2»  per  fool 

Well,  J'X24' 


Itnilllieam,  v*  per  foot 
Web,  ("x:,,- 


Wel.,rx2r  U|i.fl.,2  2i'"'2r,|.'(«angle;U|.,  fl.,  2  2"X3'l*,ingle 

ngle  ,  Uii.  fl..  2  2-x  .J    4.S#  angle       '  '^      -  ,^^  „^^  ,  ,..^_,,  (,^,^  ^,„^, 


Iliiilllieam,  fi3l«  per  foot      |  llniltbeam.  70*  per  I'... 
Web,  fxp"  j  Web,  J'xjo' 

U]..  fl.,  2  3"X3r7.7«. 


lluilt-bcam,  711,1*  per  foot 

Web,  ft'X37'" 

l'|i.  ll,  2  2"X3l'6.4#angle 


L.  fl.,  2  i"X3'  S,4#  angle 


Uii.  fl..  2  2"x  .J'4.S#  angle  ^  '  ^'^   -■'       ,:  _        ;^^^|^.  '  ^    ^^]  ]-,^  ^..  (,,^  ^,„^,^.  I  ^    „  _  ,  ^.'^j.  s.4#,„v.'-  I.  fl..  2  3'X3'  7.2*  angl 

I.,  ft.,  2  2''X3l''  v.«'1"kI<'  ,  -  -  !  

I»am,,2j«,ierf.io,  l.nilt-be.im.  ,s«  pe,  foot  I  llnil,  b.  .u„.  o;#  per  foot  '  Ilnillbeiin,  7.«  per  f-  l^nl,-lie,i,n^  Si*  pe,  loot 

Web,  l-x._s"  Well,  i-X3o-                            W  ,  b,  i '  x  ,o'                            Web,  ft'X54  Web,  rtX3,S 


llnill  beam,  S(>#  per  fool 
Web,ft-X3S"  J,, 

Up.ll,  23" X3i'7.7#. angle 
I.,  fl.,  2  3"X3",S.4#angle 


lliiill-be.im,  .Si)#  per  loot 
■Web,  ,»,"X3S' 


rV'^^^^'.-WwIeT     fl^'^r>>r,.|*angU        :;;     2V;U-<M*a,,gle:      X^  .■  l'p.  fl.!  2  2-x  3r  .M*angle    Up.  ll,  2  3-x  3"  S.4*  angle 

:"«''    t.'fl,";^-X3l^.;;!::u       ;..' fl  !:^i5,^j*3!,;;:4.^, ,.',,.,:  3"  X  3- 7.2*  V        l'l.^rx3^^*ang;,         I.,  fl.,  2  3' X  3"  7.2*  ..ngle        ...  tl.  2  3-x  3r  9*  angle       , 


1,  i.-i .*peri ib,i,.-i..,..p...io,.,  '^.......,.^.. -;--M*.-  is'ft"^.r"""""  ^!:;:-:p^-'- 

W.l'.i-^""  .      '^•'■•1'^;?".    ,._..  ,..    ,'.''';,'.,;:.,.,.,*.. ',-„,;':.rx.r„..*,K     .    rp,„.,.,l-x  3- n.7#  angle  l  U,..  H,,  2  3-x  3r"»  angle 

I    fl..  2  3'X3l-7.7#angle      1,.  fl.,  2  j"x  4' .).7# -mgle 


'"        Iw.bl'vo-  Web,  rX30'  Web,  l-x,o'  Web,  ,;,    X35 

i,-,,  ,1     .  .-y  .1"  ,  -^tt.iiiele    l'|.  fl,  2  2-x  il'  .;.•,#  .mgle    Up.  fl..  -•  ■l-x  ,' (.,7#aiigle    Up.fl.,22j    X2I    (:;» 
""^'''    I     ,1     '.  ."x  ,[•"  ,. ,«  angle     ,  1..  ll.  2  ,'■  x  ,-  ;..|»  .."Kl^'        !■■  »■.  -'  -l"  x  31"  7.7*  angle    j  I,,  fl.,  2  3"x  l'  7-2*  an; 


23 


p.mlibeaiii.  i;i«|"i  loot         Iluill  beam.  11  ;a  per  fool 
'*  Well,  rx  27-  ^^''l     


Iliiilllieam,  (■«)#  per  foot       '  llnill-beam,  -S«  pel  f. 
W.b,  \--x  io-  ,  Will,  ,■•,,' 


Uuli-beam,  S-s»  per  b.oi        '  llnilibeam,  ii4«  per  fool 
Web.  ft-X!>*- 


:*]B'::f;:;:£  ;^:ii;-':.:i'sf l^J'^v^Vis^:^'  :^v!v;^x:i  '-;"n-^i-';,;.::f  r';,:';;-i^i^;;:j::S 


Koa.lwav,  14   I'll  .11 


Ro.i  Iw.iv    ,1.  Cb-  ir. 


Rna.lwav.  18'  Clear.  Roa.lwav.  W  CI.  ai  Roa.lwav.  22'  Clear.  Roa.lway,  24'  Clear, 


U.mel 

l.ellglll. 


M 


Panel 

Length. 


T^? 


i 


i<  ^^B?*-* 


\ 


Panel      I 


Roadway,  22'  Clear. 


RoaJway.  „•  Clear.  ^^^^^ 


i 


I 


^^|^*"*Jrgp^?S!jB^*.- 


J- 


\ 


I 


) 


Lr  ■•.h  KiLulway.  w   Clear.  Roadway,  14'  Clear, 


.■■,(*  I 


"!«I 


in-  v-^i 


10"  JO*  I 


10"  ,^o#  I 


loi- jij#l 


I 


>9 


2i 


»1 


i;"4J«I,  or 
IWiill'lH'ani.  .?Sj«  pel  fiiiit 
k/    '.oa  I  I  Well,  J"X  iS" 

l|>.  a.  2  :"x-\"  !.!;»  .in};li' 
1..  tl.,  2  ;"x  jj"  ^.5«.■lll^U■ 

|i;".i:«I.  ... 

:  liuill   l.l.llll.     iSJ*    p.'l    I.I..1 

I'        !'J«I  Wfll,    \"X   iS' 

1  Tp.  II.,  2  2'y-  -r  ;,  5*  .iMv.li' 
I  1,.  11.,  r  j-vjj"  .v.';«.iivl' 
|i;-4^«I.  "i 

lj".io#I  i  \Vcl>,  J'x  iS' 

lip.  II.,  .•  j'xrj ";,.!;«  .inglc 
I  11.  II..  .•  .'"X  5*  4*anylc 

i  I.-". I  .•*!,.. I 

'  IUiill-l>c.nii,  4I#  per  foot 
loi"  jijal  I  Well,  I'Xi.,' 

]  I'p.  II.,  2  .I'x.-r.v.'i*. ingle 
I.,  n.,  J  c'x  f  4»an^;k• 
l.•"4J#I,  ..t  i-'- .i-'aj,  ,.r 
lliiilt  1>c.iin,  3>>5*  pi  1  I. ."I        r.iiili  lie.im,  |-'t«  ].et  (....i 
Well,  J"X  i.S-  '                              Wei..  1"X  -o" 
I'p.  Il ,  •  .;"x  .•!"  ).^»  .innle    I'p.  ll..  -'  -'■x.'J"  j..;"  ■'"Kie 
I,   ll.,  -■  2">i2\"  j.5«  angle    |  I.,  ll.,  2  .-'Xj' 4*  angle 

I-"  4-'*  !•  "f  ";"  i°*J.-  '" 

lliiill-lK-.im,  iSJa  p.  I  (....1      1  lliiili-lieani,  4.'J*  |.ei  P.,ii 

Will,  l"x  iS"  ;  Well,  \'x  20' 

I  p.  ll.,  -•  .'"xji"  V5#  angle  '  Iji.  ll..  -■  2~  <  2\"  v5*-'ngle 

!■  ll  ■  "  -■"■<  -T  3-5*  •■>"«'"•■      '•■  "■■  -  -""  i'  -l*  '"'y'^' 

|.-"4J#I.  ..1  ;  15"  50*  I.  "I 

l:iiili-lie.irii.  ;.iS*  1"-'  '""'      '  l'inl'l"-'>"i.  11*  P''''  f""' 

Wei),  J"xiS"  Will.  J"x:i" 

1  p.  ll..  :  .!"xjj"  v5»  angle  lip.  H.,  2  2' X  2\'  V5*  ^ngle 

1  ,  ll ,  J  J"x  j"  4#  angle         j  1..  ll.,  2  I'xf  .|»  angle 

12"  4J#I,  III  :  i>'  50#I.  iir 

lluill-lie.lln,  Vl!«  per  fmit       i  limit  tieam,  4^»  |ier  f.i..I 
Well,  }"x  l.S'  "  :  Well.  J'Xjj' 

I  p.  rt.,  2  2'y-  -•}■  ;.s#  angle    fp.  i) ,  .•  .-"x  .M"  ■,.;*  .mgli 
1  I..  II..  .'  2'x  •;■  4»  angle  '  I.,  ll.,  J  j'x  ;"  |»  angle 

I  •'  42#  J,  111  15"  50*  I.  iir 

Kiiilt-lieani,  4i#  per  fuol        j  Ituill-lieam.  .{Crit  per  (....1 

Wet.,  )"X  !.)■  i  Well,  J'x.-;' 

'  fp.  ll.,  J  .:"x.'J"  ,i.|;»aiiglei  ('p.  II.,  ;  :'x  .'J' ;,.;»  .ingle 
I  ,  ll,,  2  -'"x  f  4#  angle         ;  I.,  ll.,  •  2"  x  ;"  4*  angle 

MJ'4.-#I,  ...  I5'5'->«L"1 

|:iiili  licani.  .\:\1i  |ier  fnot      j  lluilllieani,  47  J#  |ier  I....1 
Well,  }'y  jo'  i  Well,  J-K-'l' 

I  p.  ll.,  -■  2'x  2V'  !.5»  angle     I'p.  ll..  -■  .'"xji"  V5*  angle 
1     ll.  J  j'x  i' 4#angle         !  I.,  ll. ,-•-•"  x  ;' 4#  angle 

'i"  .VJ"!.  "I  i  15'  SO*  I.'" 

ilu.ll  lieani.  4|»  pel  (mil  ,  linilllieain,  ,1.|*  pel   I....1 

Wei.,  j",-:.-!"  !  Well.  J'XJ5' 

I  p,  ll,.  ::  ;"  '  -r  i,s*an;;le    Tp.  H..  .!  .'"x -J'  ;  :;»  .mgle 


1.  ll. 


i'    i»  .I'lrl 


l„  ll.. 


,1»  ,ingle 


.  ;"  5o«  I.  1.1  I ;"  ;t*  I,  ..r 

P.iiilll.ea In*  per  r...l  Hililtlieain,  5oJ#  pel  (....l 

Will.  \"X22''  ■  Well.  J-X.'d- 

I    p    ll.  -•  J-X  -J"    J  na.iilgle  t  rpll.  J  J-x  .•)'  i,5».lllgle 

I     ll  ,.•.•■'';"  4#  angle  I.,  ll,  .■  .•' X  j"  4»  angle 


Pan-l 
LenK'li 


Roa  Iway.  I  J   Clear. 


Koailway,  14   Clear. 


Koailwa' 


iy'4.'#I." 

Iluill'lu-ain, 
Well,  \"x,i- 
Ip.  ll.,  :  .'": 
I..  II., -'  j'x 

ij'.i:»I,i, 
lUiill-lieam, 
Well,  l'Xi> 

I' p.  tl.,  J  2"> 

I.,  ll..  -•  -••x 

IJ"4J#I,  n 
t'.nilt-lieatn, 
Well,  i"xt( 
Tp.  ll,  J  -•": 
1..  ll.,  .'  j"X 

ij"  4J«I,  a 
I'liilt-lie.nn, 
Well,  1"X|, 
I  p.  ll.,  -•;": 
I.,  ll.,  J  .'"X 

!i-'"4-#I.e 

'  lliiill.l.eain. 
Well,  \'X2< 
Ip.ll.,  -•-•" 

.  I .  II.,  J  2'y. 

'  '  ':•"  .SO*  !• ' 
Hililllie.tm. 
Well.  \'X2 
l-p.  II..  .'  2- 

j  I..  II.,  J  J"X 

I  "5"  50*  I.  f 
'  Huilt-beani. 
'  Web,  1 "  <  -• 
'  I'p.  ll.,  2  2' 
I..  Il„  .'  -•"x 

I  s"  V^  I,  I 
llnill  I.,  am, 
Will,  yX2 
rp.  ll,.  -.•" 
I.,  ll.,  J  J"X 

1 1;''  50#  I.  I 
llnill-lieani. 
Well,  j'x - 
rp.ll..--.-' 
1,.  ll.,  ;  J"X 

j  15' 50*1.' 

'  Iliillllicam, 

Well,  J'x  J 

L'p.  II.,  2  2" 

I..  II..  2  'J'; 

'  1 5'  50#  I,  . 
Illl.ll-l.e.ini. 
Wei.,  i"^- 
Ip.ll.,  .-.•■ 

i  I..  11.,  2  4" 

I'.nilt-lieam. 
Well.  \"  •  .• 
rp.ll.jr 
l„  ll.  -•  .'"X 

I  lliiiUliram. 

'  Wil..  1"X2 
r,.  ll.,.. -'• 
I..  (1.,  .:  -•"  X 

I 

limli  III  ...n. 
Wei.,  \'x: 
Ip.  II,,  •  -•- 
I..  (I.,  -  -    ■ 

n.iilt  !ie,im. 

Well,  \'X2 
l-p  II,,  ..  2' 
I„  ll.  .•  -•"> 


kiw, 


TABLE    XXI. 

TABLE    OF    FLOOR    BEAMS. 

CLASS  C. 


Roiiilway,  14'  Clear.  Roailway.  16   Clear.  Koailway,  i8'  Clear. 


Roadway,  20'  Clear.  Kuailway,  «'  Clear.  Roadway,  24'  Clear.  Len"*h 


I  10"  ;o#  I 


I  10"  iri#  J 


loj"  .ill*  I 


I.'".1J#I,  (.t  I2"4J#I,  iir 

IWiilt-luMin,  ii)l#  ptr  flint      I  liuilt-lii-.nii,  .ni#  per  font 
Well,  }"xi,S'  "  i\Vel,.  I'X.V 

I'lK  II.,  .•  .•"\.-i,"  vs*  .iiiKle  I  l'|i.  II.,  2--"xjJ' j,5#,„,kIc 
I..  II.,  -  ■'-     '     -  -"  -      '        ...    -  -»--•    - 


'5".So#I.  "r  '"5"5o*I.i>r  1  1,  ■„ .  ,^        ,     , 

Huil..|Ka,„,  .,8J#  per  fn,„       1,,„|,  wL,  ;,#  p.r  f„„.        I  ''"'■''"'"'•  5^^*  1-  """ 

'■-  Wdi,  i"X24"  W.I.,  |-x,(,"  \,.,^f     ,.       ^        , 

.^  .•;■■  .VS#  .-."Kle  i  I'p.  II..  =  .-x  ..J-  j,5#  angle    I'p.  11.,  2  2" X  2]'  .v.S«.."m1'    I'l..  H.,  .-  .-'x  .^l'  ,.5#.-»nglc  I      '';,  "■;  ^.'  "^.'^ '/i  ..'''''r 
.-1    ,;..S#  .innlc    il..  ll..;:2"X.i'4#aimle  I..  11.,  j  ^'x  5' .,#  ,,nj;le  I    il,  :  ..'x  ,' 4»  .niKle        i'-""--XJt    5-,i» -"'Ble 


i.''.(2«I,  ,ir  ij",(:#I,  ..1  15"50«I.  iir  i;v5«I, ... 

Iliiill-hi.iiii,  .(o'a  i.ii  f.ii.l  nuill  I..Mni,  |-,*  per  f....t  llciilli.eaiii,  49j#  per  (....I       linh  liiani.  5)#  per  fi...t  liuilllitani,  ;;#  per  font 

Well,  J'X  IS"  Weh.  \'X2,-  I  Wei.,  i'x  .'5'  Ud.,  i"x  .f,"  1  Wel>,  i"x  -•./' 

I'p.  II.,  .' J"x.-|,     ;.!;«  ant;le  Ip.  ll., 

I.,  ll.,  .•  2'xf  I*  an 


"III.  I    *jp  ,  wel.,  I    X  jj-  Wlh,  JX-f)"  j   ■•-■■.  (    " -J 

«anj;le    Ip.  ll.,  .'  yy  ,{■■  ;.5«aii«lc  ]  I'p.  ll.,  2  .•"  X  ij' 3.^*  ai.cl.    I  p  ll.,  ..  .''X  j"  .|#  angle       i  l-'i''"--  2'x  2\' .is#  m^W 
igle^    |l..Jl.,  J.-"x.iV|«anKle  I.,  ll.,  .' j'x  /  4«  an^le  1.  ll.,  J  j'x  .J' 4.5#  angle       '■  "•.  2  J'Xjf  5.3*  .in«lc 


i;"4.'«I,..r  i5'5o«I,..i  i5"5o#I,..r  1 

r.iiilt-l.eani,  41  J»  per  f....l        Huilll.e.im,  41*  per  f..iil        '  ll.nll  lie.nn,  5oJ#  per  f....l  '''"H  I'™".  53*  \"--'  '""»        i  li"dl-lH:im.  i>i\«  per t      I 

Wei.,  1"X.-..'  Wei.,  j"Xj(j"  Wcl.,  1"X2(."  ;  Wei),  V'Xp'  !  ,y 

I'p.  ll.,  J  yx  .^J' ,,S#.'nj;l.-  ^  I  ■  "■•  - -''^•'"  ■'■5*  ••>"«'<'• 

I,.  II.,  ;  J"x  ,"  4#  angle      '  ' '  ''•  -  -I'x .V  5*  »"«!<-■ 


Wei.,  J'xio" 

I'p.  ll.,  -•  ■"Xjl"  i.5«ai.Kk     I'p,  ll,  :  ^x  .-J"  V5#  .mgle 

1    ll.,  :  -•'■  X  j"  I*  angle        ,  ]..  ll.,  .•  j  "  x  f  4#  angle 

i:' 4.-«I,  i.r  1  1 5' 50*  I.  or 

.1 


lliiill  l.e.iin.  5SI*  |.ei  li...t  r..ull-lie,iMi,  |i  la  per  fc.i.l      1  lluill-lie.iin,  .|7#  pet  f.M.I 

Wei.,  1"X  |,S-"  Wei..  l"Xi.,-"  i  Web.  1"X.'5' 

I  p.  ll,  J  j"x -J'  V5»  aiii;!.'  I  p.  ll.,  J  2"  ^  2]'  ;,.5*ani.,le  .  Up.  ll.,  2  .-"x  j  J"  3. 5*  angle 

1,.  II.,  :;  2' X  jj"  V5«  angle  I.,  ll.,  -•  -■" ^  ;,'  ;»  .mglc         1  t,.  ll.,  :  j'x 3"  4#  angle 


Well,  }'x.-4'' 

L'p.  tl.,  2  :;"x.'J"  3.5#  :int;le 

I.,  ll,  2  j"X3"4#aiii;lf 


j  i:"  4J*I.  ..r  !  t:!"  4J»I,  ..I  i  1 5"  50*  I,  ,.i 

I  llniltl.e.m.,  3^  J*  p.-i  l..'.t  '  1 '.11  ill. In  am.  \\^^  pt  r  f.ii.t        l.nilt-Iii'ani.  .(S^ft  per  f.n.t 

I  W.I.,  1  "X  i.S"  "  Wcl.,  I'^.T,"  ' 

Ip.  ll.,  J  -•■  x.-r  3  5*  aiii'l.  Ip.  ll.,  :  _■'<.''"  •,.5#  angle 

1  I,,  ll., -•  J'X.'J'' 3.5«angli  ■  1.  ll.,  .'  :  '  ^  ; '  i«  angle 

112"  4;*  I,  or  i^'^o*!.  ..r  !  15"  50*1,  (.r 

'  r.nill-l.e.iin.  3i).i*  per  f....l  llnili-lieani,  45*  per  fni.t        ,  Muilllieani,  50!*  per  P.i.l 

Wei.,  i'x  I.S"  "  Wei.,  ("x:!-  ;Weli,  l"x:o' 

I  I  p.  ll..  -■  .■"x:J-3.|;«  angle  l'p.  ll..  ;  .■■"^: 53. 5*  angle  :  l'p.  ll.,  -'  i'x  .•{"  3..>* -uml' 

I  I  .  ll.  .•  -■"  X  3"  4#  .ingle  I  1..  ll,  :!  2"  X  3-  ,#  angle  I.,  ll,  :  -'"x  3"  4*  angle 

1:"  4.'«  I,  i.r  |l5"50»I,or  15'50#I,or 

'  lluili-l.e.ini,  4i»  per  fi.i.t  '  lUiill-lieani,  41*  per  font  Kiiiltlieam,  51  J#  |)er  f.>..t 

j  Wei.,  J"x  K,'  Well,  1  ".'.-•.•-  'i  Well,  J"X-4' 

jrp.  ll,  J  J'x.-r  3.5*  angle  l'p.  ll,  .•  j"*:'."  5.i#  angle  :  l'p.  ll,  2  ^''xjj"  4.5#angli 

I.,  ll,  ;  ;"X3' 4«angle  I ,.  ll.  :  j' <  ;'  i*  angle         :  I,,  ll,  2  ifx  3' 5*  angle 

i-'l-'I.'T  i^'SO*I.'.i  !>5"50*I."i 

lliiill  he.ini,  t.'l»  per  li...t  llnill  I.Lani,  |-|3  per  (-..,1      ;  lliiilil.!  ..111,  ^.-l*  pet  (....I 

Wei..  l"x.'o"  "  Wil.,  \"y  2]'  '  Weh,  J"x.-5' 

.     l'p.  ll.  :  j'x.'l"  3.;«  .ingie  l'p.  ll,  ■  .'    ■  .M  "  3.5«  angle    l'p.  ll,  -•  j"x  .ij"  4.,#ang]. 

I  I.,  ll.  2  2'xy  4#  angle  I.,  ll.  -■  .''  ■  ;'  1»  angle  |  I,.  11.,  3  :\"Xi'  5#  angle 

H'SoWT.  nr  K"io»I.  .11  I  I,   .,   ,  .4.         ,     . 

,      ,    ,  ,^  ..    ,   ,  -         .     .  liuilt-beam,  ^5J#  per  I1...I 

I  I'.inltl.eam,  4.v(#  pet  Pi.it         lliiilt-lieani,  yiS  |ier  In..!  ,        Y"     ' 

.  1..  ll,  =  2" X  ,"  4#  angle  ;  I ,.  ll,  .'  .-X  ,    4*  a.^gle _^'"  --*'*■'    5*  ••"t^'- 


15"  5o#I,  or 

llnH'tlieani,  ,jj#  per  f..nt  ''"iH-'H'^"',  5.|J.«  per  fn.-t 

Wei.,  I'X;!,'  W.l..  l"Xj,S- 

I'p.ll,  2  2-x  ,"  l#.''ngK  "I''  "'•  -  .;"xn"l-5#-'"Kl'.- 

I.,  ll,  2  2"X2V  4.S#  :mgle  '  ■  ''■•  -  -i"^  3"  5#  •'"kI<-' 


L'p.  ll,  2  j'X^i"  4. 5#  angle 
1..  ll,  2  2'x  ;('  5.-,#  angle 


liuilt-heani,  Co*  per  font 

Wei.,  rx.P"  I        ,3' 

Up.  11,2  2"  X  3"  5#  angle 
I..  t1.,2  3"X3"5.,j«..ngle      I 


llnill  beam,  53!*  pet  I....1  KiiiU-I.e.im,  ;5i#  pet  l..nl        lUnltl.eam.  (.:«  per  f.i..t 

Web,  J"XJ(."  W.I..  t"X2,/'  .  Web,  J' X  30'' 

l'p.  ll,  2  2"X2r  4.;#.M.:l  1  |..  11,2  2-X2J'  4.5*  angle  j  l'p.  ll,  2  2i"X3"  5.5#atigle 

I.,  ll.,  2  2fxf  5#  angle  I.  ll,  2  2l"X3'  5»  .ingle         I.,  ll,  2  2i"X2J''  (..j*  angle 

llnill  beam,  544*  per  l....t  biiili-beani,  ^7*  per  |....t  llnill-beam,  (>,]k*  per  ln,.t 

Web,  J"X27''  Will,  J'Xp"  Web,  J'Xjo" 

l'p.  ll,  2  2"X2j-4.5«ai..:le  I  p.  ll,  2  2"  x  2*' 4.5*  aiigU     'l'-"-  -  :"x  3"  i*.ingle 

I.,  ll,  2  2i"Xf  5#  angle  I.  ll.  2  2'x^y  5.3#  angle    |  '•••'••  -  .: J " x  .5 '  <'';*  •'"KI'; 

liniltl.eani,  55}*  per  f....t  I'.nilt-beani,  ('k)#  ]iet  f.n.l        .  limit-beam.  '.5*  per  foot 

Web,  }"  x  28"  Well,  J"  x  30"  j  Web,  i '  x  30" 

l'p.  ll,  2  2"X2i'4.5»angl.  l'p.  II,  2  2'X3"  s*  angle       <  I  p.  ll.  2  3"x  3' ('..5*  .mgle 

I,,  ll,  2  iJ'X  3"  5#  angle  I.,  fl.,  2  3'X3"  5..j#  angle      :  I.,  ll.  2  3"X3"  7-*  "'gle 


4le 


W5-5o«I.nr  .5' SO*  I."'  H.,il,-l.e.„n.  .,l*l.erf...., 

I  llnilibeain,  .|4#  per  fnnl        '  limit-beam,  v.l*  per  font  ,,.^      ; 

Web.  J"x--."  Well,  rx2V'  ■,       ;'       -l    1-       *        1 

j  ip.  11:2  2-X2r  3.5*  angle,  up.  ll.  2_2~x  ■    4#  angle  \\ '-^VJ  ^'^  ;^.:;;t 

jl,.ll..  2  2'X3-.,#angle         j  I..  II,  2  2V' x  3' 4.4*  angle  \f-»-'--  X^J    5-.l»  .mj-l^ 

llS"i;o«T.  or  is'  so*  I.  or  1.    11  ,•         .     . 

1  ,  ,.    ,   ,  ,„         .     .        Mill     1.1  am,  ssJ*  pel  I.II. I 

1  limit  l.e.im.4^«l"r  (n-l  limit-beam.  51  i»  per  I.... 1  1  ■■  v    v" 

Web.  J"  x.. 2'  Web,  I"  X  20-  ;^''';l    ""f 

ip.ii:2  2-x2r,..».o,g.,  rp.ri.,2  2-x3  ,*.,ng,e    ';,":v,;^i^*:f 

i  I..  ,1,  2  2'x  ,-  ,«  anglc_      ,  I..  II,  2  2\-X  i    ,.,«  angb-  ,^"^^l 

limuf  .i!o.%  per  f,..,t        '  ;^:1;'^:':  ^  ^'  '''  ' '  WebT-.f  ""  '""' 

up.V2'2-x2r.vs*.>ngii  'I-''-"-  '5*-Ki.'  u,:.;i.,2  2rx.r-,...*..ngi. 


I.,  ll,  2  2'X3".,#.-ingle 


Ipil. 

1.   ll.  .'.'■■,      a  angle 


1.  ll.  2  2J"X2|"  v.(#.ingle 


gle 


IS'Sr^I,  ..r  |l!uilllK-am,  -,2'aper  b.ni  llnill  I... im,  s.S#  per  I..1.1 

ll,„lt.|ie.,m,47l*lie.  l-H        |^^.^,^^  j.,,,^^,  •  ^,^.,,,    j-,  ,,;. 

)^'''',  '"":','     I-         »  ,     il'p    ll,2  2-X2)      ,.S#.'ngle  Up.d.,2   2i-X2l",...#.mgl, 

lp.ll.22X2i     I5».i"gle     ,'„     ...,,,.^,, ,     „      .,,■■,  .r  =  ,a„.,.l,. 


I.,  ll,  2  2'x  ;•  4#  angle 


,  I..  II,  ■  .•''X3I'   ;-,#  angle       I.. 


,.  |»  .mgli 


"5'St>*I."f  :  limit  b.  ll",     '■-•  per  (....I        llnill  l..-.im.  («#  per  font 

llmll-liea ).»«  pec  f....t  ^^.^^^  _,  Web.  I'Xj.r 

T^''^""":-'  ,.       ,         ,       l'p.  ll.      ■        •       na.mgle    l'p.  11,2  2'x, i"-v.i#a..r.U 

i5"so#I,nr  ■  l;„ilt  br.im,  5s#  I'T  f""« 

biillt-beani,  5ol»  pel  |....t .,'l' 

Web,  J'X2l.'' 


;li-'  t'pll.  2  2"x  :\"  PS*  angle 


Well,  1"X2S' 

l'p.  ll. 


t'.niltbcam,  fn \1t  per  fnot 
Well,  yx  ,0' 


llmil-iie.im.  ;;#  per  |....t  Itnilt-I.i  .tm,  02#  per  b.(.t 

Web,  i"X2.)"  Web,  J''X3o'' 

l'p.  tl,  2  2"  X  2i'  4.sa  ai.fl  l'p.  ll,  2  2I"  X  3"  5.5*  angle 

I.,  ll,  2  2"X3}'  5.3#  angle  1,.  ll,  2  23"X2}"6.5#angle 

lliiill-beani,  yi#  |ier  (...  1          liniltbeain,  63^*  per  font 
Web,  I'Xjo"                                Web,  J'X  30" 
l'p.  ll,  2  2J'x  24'4.i)#ange|  l.'|..tl.,  2  2"X3'(*angle 
I.,  ll         ■       ..  -     .- 


Ilnilt'beani,  C.7J*  |.er  loot 
Well,  }'X3o" 
Up.  ll,2  3"X3"7.2«angle 
I..  11.,  J3"X3i"7.7#aiigle 

llnilt-lieain,  70*  per  foot        I 
Web,  J' X  30"  ; 

Up.  ll,  2  3"  X  34"  7.7*  angle  I 


2  2"X3J"  5.3a  angle      1..  tl,  2  24"  x  3°  (.7*  angle     ;  I,,  ll,  2  }"'<:,"  .S.4#  angl 


liiiilt  beam.  f:2*  p.  I  1 llnill-beam,  (.74#  per  font  Miiilt-beani,  71.4*  I'er  l....t      j 

Web,  i "  X  30"                            Well,  \"  X  30"  ,  Web,  ,55"  x  35"                        ; 

I'p.ll,  2  2\"x;i'  s-S#i"i-l.     Up.ll,  2  }'X]'  7.2#  angle  j  Up.ll.,2  2f  X  2}"  (i.5#angle 

I,.  II,  2  2i'x  .!i'0.5#  .oi^le  :  I.,  tl,  2  j'x  jj'  7.7*  angle  '•■  "■.  =  3'x  j"  ".-'*  anglf 

lluilt-beani,  6il#  per  f.-  1      '  liuiltbeani,  70#  pet  foot  '  llnill-Iicam,  7S#  per  font       I 

Web,  J-  X  ,o'                             ,  Well,  I"  X  30"  Web,  ,>/  X  3(1' 

'  Up.  ll,  2  3"X34'  77*  angle  I'p-ll.  2  2"X3|"  1,.  i*  .uigi.- 

I,  ll,  2  X'x  f  ,s.4#  .ingle  ;  I.,  ll,  2  i'x  X'  7.2*  .mgle 


Up.  ll,  2  2"x  \'  i*aiiL! 
I.,  ll,  2  24' X  3"  (..7*,m; 


llnill  b.  on,  (.5*  per  1.."! 
Web,  l"x  30" 
Up.  ll,  2  2"X3l  '(..4a  m. 
I  ■  ll,  23" X  3"  7.2#.nigl. 

llnill  l.i.im,  (<.l*  p.  I  !■■ 
Web,  i'Xja' 
Up.  11,2  24''X3'l..7a,i: 
I- 11-. -'j'X,3r7-7«-i".-- 


.  I 

linilt-beani.  75*  per  font        j  llnilt-be.in;,  Si«  per  foot        | 
Well,  ,\"X34''  I  Web,  ,';."X3.S'  ; 

Up.  H.,2  2fX2J"(..s* angle'  Up.  ll,  2  2'x  3!' i..4a  angle 
I,,  ll,  2  i"x  f  7.2#  angle      j  1..  ll,  2  fxf  7.2»  angle 

I  ' 

llniltbcani,  7(.la  pir  l....!         Ilnilt-beain,  .S2l#  pe'  t,...t 

'  Web,  |>,,,"X3s  Web.  ,';.,"x3S" 

I  Up.ll.,2  2i'X2(-r..j#.ingle   Up.  ll.  2  24''X3'(..7#.inglei 
I,,  fl.,  2  3"X3' 7.2#angle         I.,  ll.  2  3'x  34' 7.7*  angle 


Unilt  Iieam,  fiO#  per  (•■ 
Web,  J"X3o" 


l.S#  angle    Up.ll,  2  24"  X  i"  s.5#  angle    Up.  ll.  2  3-X3"7.2#ai 


,                                   1.,  Il.j  2->.  i|'      ;#angle       l."  ll.  2  2- x  j)' f, .,«  angle     j  l.  fl..  2  3"  x  3"  ,S..,#  .m:;i. 
I,   ll,  22    X3    4»  angle  '  ^;  __j 

Roadway.  14' Clear.  Rna.lway,  1      Clc:ir.  R.ia.lway,  i8'  Clear.  Roa.lway,  Jo' Cle.o 


llnill  beam.  7.S«  per  foot  '  linili  be.im,  .Ss#  per  I....1 
Web,  ,V."X3(.'  Web,  ,»,,"X3S" 

Up.  fl.,  2  2'x  ,1'  i..,|a.uigl.     l'|..  ll.  2  ;,'x  3'  7..'a  .mgle 
I.,  ll,  2  3"  X  3"  7.2a  angle        I  .  ll,  2  3  "  X  3"  ,S.  p-t  .iii,;li- 

Rna.lway.  12'  Clear.  Rnadwav.  24'  Clear. 


i«' 


■5 


16' 


>7' 


18' 


llnill-beam,  (xrtt  ].ei  f..nl  llnill-beam,  654*  per  fnot  I  Unill-lieain,  7S#  per  f<.ol        | 

Web,  J"X3o'  Web,  }'X3o'  Web,  ,s,,"X34'  |        ,^, 

Up.  ll,  2  2"  X  3- 5a  .ingle  Up.fl.,2  3'X3-|..5«angle  li'.  ll,  2  jj'x  2j- b.saangle' 

I.,  fl.,  2  3'X3"  5,>)#angle  1..  fl.,  2  3- x  3- 7.2a  angle  I  .  ll,  2  3' X  3"  7,2*  angle      | 


»3 


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TABLE     OF     LATERAL     SYSTEMS     AND     SWAY     BRACINr, 


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TABLE    XX 

TABLE     OF     LATERAL    SYSTEMS    AND    SWAY     BRACINt'i 


IMNKt.  7. 


I'ANII     I. 


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109.69 

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TABLE    FOR    FINDING    THE    NECESSAKY 


TABLE   XXV 


WIDTH    OF    BE 


Having 

given  the  total  pressure  on 

said  s 

urface, 

and  the  diameter  of 

the  pi 

n.       This  table  is  calculated  for  a  working  comipressive  stress  of  6  t 

Vertical  1  les  of  inches  show  width 

CT.A.SS    A. 

■i" 

•r' 

li" 

H" 

2" 

2i" 

zi" 

2|" 

2i" 

1 

2i" 

2f 

2F 

f 

3*" 

3r 

3*"         i" 

31' 

3r 

34" 

4- 50 

4.88 

5-25 

5-63 

6.00 

6.38 

6.75 

7-59 
8.44 
9.28 

7-13 

7.50 

7.88 

8.25 

8.63 

9.00 

9-38 

9-75 

10.13       ).5o 

10.88 

11.25 

11.63 

5.06 

S.48 

5.91 

6.33 

6.75 

7-17 

8.02 
'8.91  ' 

S.44 

9-37 

8.86 

"9.84 

10.83 

9.28 

9.71 

10.12 

10.55 

10.97 

n.40 

:.8i 

12.23 

12.66 

13.08 

i" 
H" 

S'63 

6.oq 

"  6.57^ 

7-03 

7-5° 

7-97 
8.77 

10.31 

10.78 

11.25 

11.72 

12.19 

12.66 
13-92' 

;-i3 

1359 

14.06 

^•53 

6.19    i      6.70 

7.22 

7-73 

8.25 

9.80 

10.31 

11-34 

11.86 

12.38 

12.89 

13-41 

:44_ 

14.95 

15.47 

1 5^98 

6.75    1      7.31 

7.88 

8.44 

9.00 

9-56 

10.13 

10.69 

11.25 

II. 81 

12.38 

12.94 

13.50 

14.06 

14.63 

15-19         -75 

10.31 

16.88 

17.44 

"7-31    i      7^92" 
7.88    1      8.53 

S.AA     i          O.U     i 

8-53 

9.14 

9-75 

10.36 

10.97 
11.81 

11.58 

12.1)1 

12.80 

13-41 

14.02 

14.63 

15-23 

15.84 

16.45         .06 

17.67 

18.28 

18.89 

9.19 

9.84 

10.50 

II. 16 
~  11-95 

12.47 

I3.I.. 

13-78 

14.44 

15.09 

15.75 

16.41 

17.06 

17.72        1.38 

19.03 

19.69 

20.34 

Q.84 

lO-SS 

11.25 
12.00 

12.66 

-  '3-36 
14.25 

14.06 

14-77 

15-47 

16.17 

16.88 

17-58 

18.28 

18.98        1.69 

20.39 

21.09 

21.80 

l"            1        Q.OO 

9.75    '     lO.W 

11.25 

12.75 

13-50 

14.99 

15-75 

16.50 

17-25 

18.00 

18.75 

19-50 

20.25 

.00 

21.75 

22.50 

23.25 

iX"     !     9.56 

i"o.:i6   '■■ 

"  II. 16' 

"•95 

..■.-•7S__ 
13-50 

13-55 

14-34 

15.14 

15-93 

16.73 

17-53 

18.33 

19.13 

19.92 

20.72 

21.52 

•31 

23.11 

23.91 

24.70 

"ij"      ''    10.13       '°-'5'   ' 

1T.81  " 

12.66 
^  13-36  " 

14-34 

15.19 
16.03 

16.03 

16.87 

17.72 

18.56 

19-41 

20.25 

21.09 

21.94 

22.78     ; 

:63. 
•94 

24.47 

25.3' 

26.16 
27.61 

TX""  ■  '  io.6q~ 

11.58  j    12.47 

1425 

15-14 

16.92 
17.81 

17.80 

18.70 . 

19-57 

20.48 

21.38 

22.27 

23.16 

24.05 

J'S-»3_ 

26.72 

1      11.25 

12.19   1     '313 

14.06 

15.00 

15-94 

16.88 

18.74 

19.69 

20.63 

21.56 

22.50 

23.44 

24.38 

25-31 

1.25 
•56 

27.19 

28.13 

29.06 

1    u,S 

12.S0    1     n.78 

1477 

15-75 

16.73 

17.72 

18.70 

19.67 

20.67 

21.66 

22.64 

23.63 

24.61 

25-59 

26.58 

28.55 

29.53 

__30:52  . 

if"            12.38 

I'i.''    ' 

'341 

14.44 

15-47 

16.50 

17-53 

18.56 

19.59 

20.61 

21.66 

22.69 
23.72 

23.72 
24.80 

24.75 
25.88 

25.78 
26.95 

26.81 
28.03 

27.84     ; 

.88 

29.91 

.^J°i94_ 

_3h97_ 

14.02 

15.09 

16.17 

17-35 
18.00 

._''1:.3J3_ 
19-13 

19.41 

20.48 

21-55 

22.64 

29.11    J 

.19 

31.27 

32-34 

33^42 

16.88 

20.25 

21.38 

22.48 

23-63 

24-75 

25.88 

27.00 

28.13 

29-25 

J°i38  -^ 

•55L 

32-63 

3i75 

34.88 

20.52 

21.94 

33.16 

24.36 

25.59 

26.81 

28.03 

29.25 

30-47 

3'-69_ 

32-91     , 

•13  _ 

■75 

35^34 

36^56 

37^78 
40.69 









23-63 

24.94 

26.23 

27-56 

28.88 

30.19 

31-50 

32.81 

34-13 

35-44     , 
37-97    , 

38.06 

_  39-38  _ 

I  J" 

--  - 

26.72 

28.10 

29-53 

30-94 

32-34 

33-75 

35.16 

_j6i56__ 

40.78 

42.19 

43^59 

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29.97 

31-50 

33-00 

34-50 

36.00 

37-50 

_J9-84_ 

42.19 

.  J9-oo^ 

40.50     ».0"   1 

43^50 

45.00 

46.51 

35-06 

36.65 

„38/2S„ 

41.44 

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46.22 
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47.81 
50-63 

49.42 

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61.88 

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3i" 

3i" 

"3l" 

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4" 

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1 

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1 

1 

1 
1 

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— . 

TABLE   XXVI. 

^    WIDTH    OF    BEARING-SURFACE    AT    EACH    END    OF    PINS, 

g  coniipressive  stress  of  6  tons  per  a"  on  the  projection  of  the  semi-intrados  upon  a  diametral 
[  les  of  inches  show  widths  of  bearings. 

CTASS    A. 

plane. 

Upper  horizontal 

line  shows  diameter 

of  pin. 

i" 

31' 

31' 

34" 

4" 

4F 

4k' 

41' 

4i' 

4f' 

4}' 

4F 

5' 

54' 

Si' 

51' 

5i' 

5l" 

5J" 

54" 

6" 

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10.88 

11.25 

11.63 

12.00 

12.38 

12.75 

13-13 

13-50 

13.88 



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12.23 

12.66 

13.08 

13-50 

13.92 

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15.61 

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•'3 

I3S9 

14.06 

M-53 

15.00 

15-47 

15.94 

16.41 

16.88 

17-34 

18.28 

20.63 

•44 

14-95 

15-47 

15.98 

^6.50 

17.02 

17-53 

18.05 

18.56 

19.08 

19-59 

20.11 

W 

75 
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10.31 

16.88 

17.44 

18.00 

18.56 

19-13 

19.69 

20.25 

20.80 

21.38 

21.94 

22.50 

23.06 

23-63 

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17.67 

18.28 

18.89 

19.50 

20.11 

20.72 

21-33 

21.94 

22.54 

23.16 

23.76 

24.38 

24.98 

25-59 

26.20 

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4" 

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19.03 

19.69 

20.34 

21.00 

21.66 

22.31 

22.97 

23-63 

24.27 

24.94 

25-59 

26.25 

26.91 

27-56 

28.22 

28.88 

29-53 

1.69 

20.39 

21.09 

21.80 

22.50 

23.20 

23-91 

24.61 

25-31 

26.01 

26.72 

27-42 

28.13 

28.83 

29-53 

30-23 

.30.94 

31.64 

32-34 

l" 

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21.75 

22.50 

23-25 

24.00 

2475 

25.50 

26.25 

27.00 

2774 

28.50     29.25 

30.00 

3075 

31-50 

32.25 

33.00 

3375 

34-50 

35-25 

36.00 

■31 

23.11 

23-91 

24.70 

25.50 

26.30 

27.09 

27.89 

28.69 

29.47 

30.28 

31.08 

31.88 

:,  ■■'^'■ 

33-47 

34-27 

35-0' 

35-86 

36.66 

37-45 

_3?f5_ 
40.50 

IT^" 

■94 

24.47 
25.83 

25-3' 

26.16 

27.00 

27.84 

28.69 

29-53 

30.38 

31.21 

32.06 

32.90 

33-75 

34-59 

35-44 

36.28 

37-13 

37-97 

38.81 

39-66 

26.72 

27.61 

28.50 

29-39 

30-28 

3'-'7 

32.06 

32-94 

33-84 

3473 

35-63 

36-52 

37-41 

38-30 

39-'9 

40.08 

40.97 

41.86 

4275 

'A" 

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•S6 
.88^ 

27.19 

28.13 

20.06 

30.00 

30.94 

31.88 

32-81    i    3375 

34.68 

35-63 

36.56 

37-50 

38-44 

39-38 

40.31 

41-25 

42.19 

43-13 

44.06 

45.00 

I}" 
'A" 

•r 

lA" 

•i" 

ir 

'f 

28.55 

29-53 

30.52 

3'-50 

32-48 

33-47 

34-45 

35-44 

36.41 

37-4' 

38-39 

3938 

40.36 

41-34 

42.33 

43-31 

44-30 

45-28 

46.27 

47.25 

29.91 

30-94 

3 '-97 

33-00 

34-03 

35-06 

36-09 

37- '3 

38-15 

39- '9 

40.22 

41.25 

42.28 

43-31 

44.34 

45-38 

46.41 

47-44 

48-47 

49.50 

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31-27 

32-34 

33-42 

34-50 
36.00 

35-58 

36.66 

3773 

38.81 

39-88 

40.97 

42.04 

43- '3 

44.20 

45-28 

46.36 

47-44 

48.52 

49-59 

50.67 

5175 

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32.63 

3375 
36.56 

34-88 

37-t3 

38-25 

39-38 

40.50 

41.62 

42-75 

43-87 

45.00 

46.13 

47-25 

48.38 

49-50 

50-63 

5175 

52.88 

54.00 

•'3. 

75 

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35-34 
38.06 

3778 

39.00 

40.22 

41.44 

42.66 

43.88 

45-08 

46.31 

47-53 
51..8 

48.75 

49-97 

51.19 

52.41 

53-63 

54-84 

56.06 

57-28 

58.50 

39-38 

40.69 

42.00 

43-31 

44-63 

45-94 

47.25 

48.55 

49.88 

52.50 

53-8' 

55-13 

56.44 

5775 

59.06 

60.38 

61.69 

63.00 

40.78 

42.19 

43-59 

45.00 

46.41 

47-Si 

49.22 

50.63 

52.02 

53-44 

54-84 

5"6-25 

57.66 

59.06 

60.47 

61.88 

63-28 

_  64.69 
69.00 

66.09 

67.50 

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43-50 

45.00 

46.51 

48.00 

49-50 

51.00 

52.50 

54.00 

55-49 

57.00 

58.49 

60.00 

61.50 

63.00 

64.50 

66.00 

67.50 

70.50 

72.00 

2" 

1      2i" 

i      2i" 

•63 

46.22 

47.81 

49-42 

51.00 

52.59 

54-19 

55-78 

57-38 

58.96 

60.56 

62.15 

63-75 

65-34 

66.94 

68.53 

70.13 

71.72 

73-31 

74.91 
79-31 

76.50 
81.00 

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50-63 

52-32 

54.00 

55-69 

57-38 

59.06   ]    60.75 

62.43 

64.13 

65.81 

67.50 

69.19 

70.88 

72.56 

74.25 

75-94 

77-62 

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51.66 

53-44 

55-23 

57.00 

58.78 

60.56 

62.34    1     64.13 

65.90 

67.69    :     6946 

7'-25 

73.03 

74-81 

76.59 

78.38 

80.16 

81.94 

83.72 

85.50 

2J" 
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54-3« 

56-25 

58.14 

60.00 

61.86 

6375 

65-63    ,     67.50 

69-37 
72-83 

71.25 

73-»« 

75-00 

76.S8 

78-75 

80.63 

82. 50 

84-38 

86.2  5 

88..  3 

90.00 

■',i 

57.09 

59.06 

61.04 
63:95^ 

63.00 

64.97 

66.94 

68.91    I     70.88 

74-81 

76.77 

78-75 

80.72 

82.69 

84.66 

86.63 
90-75 

83.59 

90.56 

92.53 

94-50 

6 1. 88 

66.00 

68.06 

70- >  3 

72.19  !   74.25 

76.30 

78.38- 

80.13 

82.50 

84.56 

86.63 

88.69 

92.81 

94.87 

96.94 

99;«00' 

•■4      »._ 



69.00 

71.16 

73-i' 

75-47 

77-63 

79.77 

81.94 

84.08 

86.25 

88.41 

90.56 

92.72 

94.88 

97-03 

99.19 

iot.34 

-i°57/r 

lyf<Xl6 

fi  14.56 
118.97 

/ioj-jo 
lOiS.oo 

24" 

J 

-— - 

74-25 

76.50 

78-75 

8r.oo 

83-24 
86.71 

85.50 
89.06 

87.74 

90.00 

92.25 

94-50 

96.75 

99.00 

101.25 
105.47 

103.50 
107.81 

112.12 



82.03 

84.38 

91.40 
95-05 

9375 
97-50 

96.09 

98.44    ;   100.78 

'03.13 

1    IIJ.W 

3i" 



90.18 

92.63 

99-94 
103.78 

102.38    1   104.S1 

107.25 

109.69 

i  11 --00  '    r,i" 

■ 



98.71 

101.25 

106.31       108.84 

111.38 

115.50" 

119.63 

113.91 

I  18. 1-!, 
I  22.^4 

II  6^44 

i  '2'-5>-'  1:   Xi" 

107.64 

ito.25    i  112.88 
1 16.91 

■'_-0.7i_ 
125.06 

123-38 

'     120  0 

4' 

127-78 

i     130.50 
j     '3500 

J' 

3*" 
3i" 

1    4' 



12375 

I26A6 

129.37 

132.19 

1 

1 

133-69 

136.59 

139-50 

i 

1 

i 

i 

1 

1 

144.00 

♦ 

\ 

■ 

31" 


12.19 

"1371 


XVII. 

'    BEARING-SURF 

•ompressivc  stress  of  7.}  Don   a   diametral   plane.     Upper 
lines  of  inches  show  vvidl 

AND   C. 


I 


f     I 


0' 


TABLE   XXV 

TABLE    FOR    FINDING    THE    NECESSARY    WIDTH    OF    BE 

Hiving  given  the  total  pressure  on  said  area,  and  the  diameter  of  the  pin.       This  table  is  calculated  for  a  working  compre: 

horizontal  line  shows  diameter  of   pin.     Vertical  lines  c 

CLASSES  B   AND 


TABLE   XXVII. 

'    WIDTH    OF    BEARING-SURFACE    AT    EACH    END    OF    PINS, 

ted  for  a  workinj;  compressive  .stress  of  7.}  tons  per  n"  on  the    projection  of   the    semi-intrados    upon   a   diametral    plane. 
r  of   pin.     Vertical  lines  of  inches  show  widths  of  bearings. 

CLASSES  B   AND  C. 


Upper 


-i" 

3"       ' 

-1 

3i" 

3i"     1 

3r 

12.66 
14-24 

3i" 

.1* 

3:1" 

7,1" 

"4-53 
16.35 
18.16 

4" 

4J" 

4i" 

41" 

4r 

4-3" 

A\" 

4i" 

5" 

A" 

¥ 

H" 

4" 

W 

V 

10.78 

1 
11.25 

12.66 

11.72 
13.18    : 

r2.i9 
13-7' 

13-13 

>3-S9 

14.06 
15.82 

15.00 

_'S:47_ 
17.40 

J5:?4  . 

17-93 

16.41 

16.88 
18.94 

21.09 

J7-34 

19-S' 
21.68 

„-3:^5_ 

26.02 
^8.18 

17.81 
20.04 

18.28 

18.7s 
21.09 

23-44 
25-78 
28.13 

30-47 
32-81 

12.13 

_  ■4-77_ 
16.41 

~i8^r 

19.69 

21-33 

15.29 
16.99 
18.69 

„-°-39__ 
22.09 

16.88 

18.46 

20.57 

13.48 

14.06 

14-65  ; 

'5-23 
16.76 

1S.28' 

19.S0 

i5.82_ 
17.40 
18.98 
20.57 

17-58 

18.75 
20.63 

>9-34 

19.92 

20.51 

22.27 

22.85 

14.S2 

15-47 
16.88 

16.11  1 

19-34 

.9.98 
2 1. So 
23.61 

21.37 

21.91 

23-9' 
25.90 
27.89 
29.88 
31.86 
33-87 

22.56 
24.61 
26.66 
28.7. 

23.20 

'  25-3^1  ' 
27-42 
29-53 

24-49 

25.14 
27-42 

16.17 

17-58  . 

21.09 
22.85 
24.61 
26.37 
28.13 

22.50 
24.38 

23.20 

25-14 

27.07 

26.72 

17-52 

18.28 
"19.69 

19.04  1 

21.97 

28.9s 

29.71 

18.87 

21-33 

22.15 

22.97 

23-79 

25-49 
27.19 

25-43 

26.25 

30-35 

3i-'7 

31-99 
34.28 

36-56 
38-85^ 

20.21 

21.09 

22.S5 
24.38 

25.(JO 

27.42 

23-73  . 

25-3' 
26.89 

24.6  r 
26.25 
27.89 

27-25 

29.06 

"30.88~ 

28.13 
30^00 
3f.88 
33-75 

29.00 
>-94~" 

32.87 

30.76 
32-81 

.3' -64^ 

33-75 

32-52 
34-69 
36.S6  ' 
39.02 
41-19 

33-40 
35-63 

37-85 

3S-'6 

I" 

21.56 

22.50_ 

23-9" 

25-3' 

"26.72 

28..  3 

29-53 

23-44 
24.90 
26.37 

27-83^ 
29.30 
30.76 

_32-23 

33-69 

_35d'> 
38.09 

41.02 

43-95 
46.S8 
49.80 

37-50 
39-84 
42.19 

22.91 

28.89 

29.88 

34-86 

35.86 

•A" 

li" 

24.26 

28.48 

29-53 

3'-i7 

«32.8i 

30-59 

_32.29 

33-98 

31.64 

32.70 

34.80 

35-86 

36.91 

37-97 

40.08 

41-13 

25.61 

28.95 
30-47^ 

3' -99 
3.3-52 

_30.o6_ 
31.64 

33-22 

34-80 

.   3^-39  . 

37-97 

33-40 

.35-'6_ 

36.91 

_  34-5J__ 
36-33 
38.14 

35-63 

36-74 

37-85 
39-84 
41.84 

38-96 

40.0S 
42.19 

42.30 
44-53  " 

43-42 

44-53 

lA" 
li" 

lf^T" 
li" 

26.95 

37-50 
39-38 

_j8-_f'7_ 
40.61 

41.02 

43-07 
45.12 

43-36 
45-53 
47.70 
49.86 
52.03 

45-70 

46.88 
49.22 

28.30 

34-45 

35.68 

-44-30^ 
46.41 

48.52 

46.76 

47-99 

29.65 

30-94  , 
32-34 

33-75 
36.56 

_39^38_ 
42.19 
45.00 
47.8. 

_36-oj)_ 
37-73 

37-38 
39.08 

38.67 

39-96 

41.25 
_J3'L3_ 
45.00 
48.75 
52-50 
5'-25 

42-54 
44-47 

43-83 

48.98 

_  S?-_27__ 
52-56 
54.84 

51-56 

31.00 

35-04 
36- S6 

40.43 
42.19 

.._4i78_ 
43-59 
47-23 
50.86 

45-82 

47-17 

51.21 

53-9I 
56.25 

•A" 

•i" 

,r 

If" 

•r 
2" 

"2i"      ' 

1--.14 

39-38 

40.78 

50.27 

54-14 

58.01 

47-81 
51.80 

49-22 

53-32 

50-63 
54-84 

53-44 

')5-04 

39.61 
42.66 

4i-'3 

42.66 

44.18 

45-70 

56-37 

57.S9 

59-41 

60.94 

37-73 

44-30 

45-94 

47-58 

49.22 

55-78 

57-42 
61.52 

59.06 

60.70 

62.34 

63-98 

65-63 

40-43 

45-70 
48-75 
5' -80 
54-84 

47.46 
50-63 

49-22 

52.50 

50.98 

52-73 

54-49 

59-77 

63.28 

65.04 

66.80 

68.56 

70-31 
79-69 

43- '3 

54-38 

56-25 

..J8:i2_ 
61.76 

60.00 
"^63.75 

67-50 
71.25 
75.00 
78.75 

61.S8 

65-74' 
69.61 

63-75 

65.63 

67-50 

69-38 

71-25 

73-'3 

53-79 
56-95 

^55-78 
59:06 

57-77 

59-77 

67-73 
71.72 
75.70 

69-73 

71.72 

73-71 
78.05 

75-70 

77-70 

61.17 

63.28 

65-39 
69.02 

73-83 

75-94 

So.  16 

82.27 

84-38 

2\" 

2r 

6o.i2_ 

62.34 

__-^i-S7__ 
67-97 

66.80 

73-4« 
77-.?4 

77-93 

80.16 

82.38 
"86772 

84.61 

86.84 

89.06 





70.31 

72.66 

79.69 
83-67 

82.03 

86. 1 3 

_„90^3„ 

94-34 

84-38 
88.59 
92.81 

S9.06 
93-52 

91.41 
95-98 

93-75 
98.44 

2i" 
2|" 
2j" 

73-83 

76.29 

81.21 

91-05 
95-39 



, 

82.50 

85.08 
8S.95 

87.66 
91.64 

97-97 

100.56 

103-13 

_       





97-03 

99-73 
104.06 

108.40 

102.42 

105.12 

107.81 



^-.   -  — 

98-44 

101.25 

106.8S 

109.69 

112.50 
117.19 

3" 

3i" 
3i" 

3i" 

—      — 

105.47 

i"-.\3 

114.26 
118.83 





115.78 

121.86 

123.40 

126.56 

I 


■li 


,-•"[.(•. 

'5"[     ' 

F 

Thick-    1 
ness  of  j 
Web  in 

Inches. 

0.250 

_i'l?7S 
0.300     1 

_o.3-'5 

1  0.350 
'  0.375 

1  0.400 

L?4-'5    ! 
|_o.450 

1  0.475 
0.500 

;     0.525      i 
0.550 

!    0.575 

0.600 
i    0.625 

0.650 

L2:^7'5 

'  0.700 

i  "0.725 
'0.750 

0.775 
i_o.8oo 

p 

w 

A 

F 

W 

A 

oo 

— 

60, 

,^54 



106 

1 

«*J 

f«, 

30.00 

3072 

3 '-72 
3--7-' 
3.5-72 

'^2.7f~ 

2-73 

2-75 
2.7S 

2.80 
■"2.S3" 

2.«5 

2.S.S 

2.93 
2.95 

^^-'^ 

3-00 

303 
3-05 

3.08 

__3-'o 

.l-'5 

3-20 

354 

9.00 
9.22 

y-52 
9.S2 ' 
10.12 
ro.42 

— - 

I06 

\ 

40.00 

r  4 1.25" 
1  42.50 

1    43-75 

4500 

:    46.25 

!    47.50 

._4«75. 
5000 

~S'-2S~ 

52-50 

53-75 

55-00 

j    56-25 

i    57-50 

L..,5f<-75 
60.00 

3-53 
3-5f' 

,^58 

3.61 

3X)C 

3.68 

3-7' 
3-73 

(XD 

35 

12.00 
^  12.3s 

-2.75 

'3-13 

'3-5° 
13.88 

14.63 

15.00 

"15.38^ 

10 

3472 

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37-72 
3«:72 
3<>72 
40.72 

14--72 
43-72 
44.72 

85 
6o'~ 

35 
10 

10.72 
11.02 

II.J2  . 
11:62 
I  1 .92 
12.22 

»2.S2 
12.82 
13-12 

3-76 
3.78 
3-81 

•— ' — 

'575„ 
r6.i3 

1.3-42 

16.50 

3-83 

0.825 

_4.S72 

_  46.72 

47-72 

4S.72 

49.72 

13-72 
14.02 
14.32 

14.92 

16.88 

3.86 
3.88 
3.01 

3-').i 

0.850 

_o^75 

0.900 

^0.925 

"  0950 

-■— 

17-25 
<7-<>3 
18.00 

i\ 


k  I 


» 


~rr 


Thick-  I 

Web  in  I 
Inches. 


4"  [•-■'• 


W 


605 


1.S2 


0.0:5 


0.67 


I' 3' 

1.92 

6.71 

2.03 

7.00 

2.10 

os-^ 


■1"  £■/■■■ 

5"[-'- 

F 

ly 

A 

2.13 

2-23 

2-33 

F 

'■75„ 

'•77 

1.80 

1.83  " 
1.8s 
1.87 
1.89 

IF 

7-02 

744 
7.8s 

8.27 

A 

2.1 1 

-  ■  F-- 

1.62 

7.08 

.-•4i_! 

7-74 

1.69 

2.24 

7-36I 
2.49 

1.65 
1.67    1 

1 72 

I-74 

1.70 

8.0S 
8.4 1 

2.43 

2-53 
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••77 



1 

8.74 

^ 

1 

9.00 

^•1°^. 





—  — _- 

i 



1 

1 

-    - 

— 

1 

— ^ 

1 



— 

j 



i 

1 

1           

i 

i 

— — 

1 

1 



1 

— 



1 



i 



1 

1 

1 

i 

!              i 

_ 

0.050 


•f  - 


5"C    ■' 

1 

5"  [  ■  ^'•■ 

i^ 

,"  [  , ./. 

(,"  [  .  //. 

/• 

IF 

j1 

W 

A 

F 

1.94 
..96 

A 

F 

IV 

10.46 
1096 
11.4(5 
II  96 
12.46 
1296 
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A 

3  '4 
329 
3-44 

.rs9 

374 
3-89 
4.04 

'•"S 

7-02. 

744 

7-8S 

3.11 

1.69 

9.08 

273 

2.S5 

2..;8 
3.10 
3-23 

8. 58         2.57 

1.81 
1.84 
1.86 

— 

1 77" 
1.80 

2.24 

'2.36" 

2.49 

172 
1.74 

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950 
9.91 

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11.17 
11.58 

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2.72 
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1.S3 

8.27, 

2.01 
2.04 

1.85 

1 

1,87 

1.89 

. 

3-3S 
348 
3.60 

_  2J36  _ 

. /2°9 
2.11 

j 

. 

/  ! 

1 -^ 

! 

12.00 
12.42 
12.83 

'3.2  5 
.3.68 

14.00 

1 

13.96 
14.46 
14.96 

4.19 

tt-34_ 

449 

479 

- 



373 
3.85 

2.14 



2.16 

3.9« 

2.19 
2.21 

_2l2.3_ 

15.46 



'4.20 







—     .-. 





1 



1    _ 











1 

, 

— 





, 

1 



L  ..  .^ 



- 

— 

— . 



— 



— . 



— 





— 



-  , 

1 

1 





. 



i 

. 

i 



1 

- — 

--- '.    ..-- 

1! 

1 

M-auM- 

.    FINDING 

the   \vcij;ht   per 

TABLE    XXVIII. 

THE    DIMENSIONS    OF    UNION 

oot  in  pounds,  A  the  area  of  section  in  square  i 

IRON    MILLS'    CHANNEL    BARS 

nches,  and  F  the  width  of  flange  in  inches. 

, 

7"  [./.'. 

S"[.W. 

S"  [  .  />'. 

y"  [  •  ^-i- 

9"  [  •  /"- 

10"  [  .  A. 

10"  [  .  /.'. 

'     \      .1      \      /■• 

ir 

^i 

A 

IV 

A 

/'• 

t 

A 

/ 

;v        A 

F 

ly 

A 

F 

IV 

A 

/ 

I  -    .- 



r- 

2.30 
2.32 

— 



12.79 

J.84_l      2.02      ]_  _     __ 
4.04          204    .j     16.00 

4.80 
'4.98 
"    S..8 - 



5-40 

2.43 
2.45 

2.52 

0.) 

„4^3 

2.30 

13.46 

"7-50 

5-25 

2. 

68    1      4.40 

2-33 

i4-«3 

4.24 

2.10 

16.59 

14-50    1     4-35 

2.50 

5-58 

16.00 

4.80 

18.33 

S-So 

2. 

j6 

01 

4.58 

14.79 
1546 

__4:44_ 
4.64 

'7-25 

2-35 

i9-Jo 

_.__S-.8J_ 
6.03 

2.48 
2.50 

19.17 

5-75 

■^ 

4-75     i      2.3S 

2. 1 2 

17.92 

5-38 

237 

20.10 

20.00 

6.00 

2. 

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2.40 

- 

18.59 
•9-25 

s-ss 

2.40 

2.42    1 

1 

20.85 

6.26 

2-53 
2-55 
2.58 
2.60 
2.63 
2.65 
2.68 

20.83 

6.25 

2 

5. 10 

2.43 

5  78 

21.60 

6.48 

21.67 

6.i;o 

2. 

'59. 
'7 

3i_ 

)2 

5.28 

2-45 

19.92 

S-98 

2-45 

2.47 
2.50 

_22-35_, 
23:10 

23.85 
24.60 

_^S-3S_ 
26.10 
26.85 

671 

6-93 
7.16 

22.50 

6-75 

2. 

S-(5 

2.48 

20.89 

6. 1 8 

23.33 

7.00 

2.( 

563 
5.80 

^i5°   . 
2-53 

.^"55 

21.25 
21.92 

~22.^ 

6.38 



24.17 

7.25 

2.( 



6.58 

2.52 

...   ..„ 

7-38 

25-00 

7-50 

2.( 

6.78    1      2.55    I 



7.61 

25-83 

7-75 

2.( 



23.26 

6.98 

■^■57 
2.60 
2:62  " 

7-83 
8.06 

2.70 
2-73 

26.67 

8.00 

1    • 

23.92 

7.18 

... 

27-50 

8.25 

2-; 

i 

2459 

7.38 

27.60 

8. 28 

2-75 



28.33 

8-50 

1  ■ 





!    25.25 

7-58 

2.65 

28.35 

8.51 
8.73 
8.g6 

2.78 
2.80 

29.17 
30.00 

8.75 

2.- 

1      25'92 

778 

2.67 

29.10 
29.85 

9.00 

2.{ 

1  26.59 

7.98 
8.18 

2.70 



2-83 









!  27.25 
i  27.93 

2.72 





i 

1 

8.38 

-^_._-jZ5___ 





1 





~- 

1 





_ 

( 
1 

1 

1 

1           " 











1 







— 



1 

1 

1 

, 

s. 


A 

10'  [  .  /.'. 

10"  [  .  C. 

12"  I.  A. 

12"  [./,'. 

.2"[.C. 

•5"L     '' 

Thick- 
ness of 
Web  in 
Inches. 

F 

W             A 

F 

W 

A 

F 

W 

A 

F 

W 

A 

F 

w 

A 

F 

vv 

1 

A 

/'■ 

0.250 

20.00 
20.67 

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1    0.275 
1    0.300 
1    0.325 
1    0.31:0 

17-50 

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2-43 

2.56 

2.52 

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5-50 

2.46 

6.20 

2.58 

20.00 

6.00 

3-01 

22.54 

6.76 

3-01 

19.17 

5-75 

2.48 

21.50 

6.45 

2.61 

i    23.54 

706 

3-04 

i 

20.00 

6.00 

2-5' 

22.33 

6.70 

2.63 

1    24.54 

736 

3.06 

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1    0.37s 
i    0.400 

20.83 

6.25 

_  2  53 
2.56 

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2.66 

!  _..=5-54 

__26.54_ 

27-54 

7.66 
7.(u) 

8.2'^ 

_309 
3" 

i 



21.67 

6.i;o 

24.00 

7.20 

2.68 

30.00 
3072 

0425 

22,50 

6.75 

2.58 

24.83 

7-45 

2.71 

3-'4 

9.00 
9.22 

2-7' 

0.450 
i    0.475 
1    0.500 

|..°_-S25 
1   0.550 

0-575 
0.600 
0.625 

n-ii 

7.00 

2.6, 

1    25.67 

7.70 

2-73 
2.76 
2.73 

28.54 

8.50 

3.16 

2-73 

1 

■     ■ 

24.17 

7.25 

2.63 

1    26.50 

7-95 

29-54 

8.86 

319 

3'-72 

9.52 

2-75 

1 

25.00 

7-50 

2.66 

!  27.33 

8.20 

_32-72 

33-72 

9.82 

2.78 

40.00 

12.00 

3-53 

2S-«3 

7-75 

2.68 

28. 1 7 

:    29.00 

8.45 

2.8 1 

i 

1 

10.12 

2.80 
2-83 

41.25 

12.38 

3-56 

26.67 

S.oo 

2.71 

8.70 

2.S3 

2.86 



34-72 

10.42 

42.50 

'2-75 
'3-'3 

3-58 
3-6. 
3-63 

27.50 

8.25 

2-73 

L29-83_ 
i    30-67 

8-95 
9.20 

35  72 

10.72 

2.85 

43-75 

28-.33 

8.50 

2.76 

2.88 
2  91 

.36-72 

M.02 

2.88 

45.00 

'3-50 

t 

-.-?-i7_, 
30.00 

8.75 

2.78 

31-50 

9-45 

37-72 
38-72 

11.32. 

2.90 

46-25 

13.8S 

3.66 

0.650 
0.675 
0.700 

!?•_"- 5 
0.750 

0775 
o.Soo 

9.00 

2.81 

l,--2,l 

9.70 

2.93 



i               1 

11.62 

2-93 

47.50 

'4-25 
14.63 

3.68 
11^ 

__2,2,-'^l 

9-95 

2.96 

1 

i 



39-72 
40.72 
41.72 
42.72 

ir.92 

2-95 

1  48.75 

34.00 

10.20 

2.98 

. 

12.22 

2.98 

5000 

15.00 
'5-38 

3-73 

_34;83^. 

10.45 

_3:0L_ 

12.52 

3-00 
3-03 

_5i:2S  _ 
52-50 

3-76 
3-78 

12.82 

'5-75 

43-7^ 

13.12 

3-05 
3.10 

53-75 

16.13 

3-81 

1 

44.72 

13.42 

55-00 
56-25 
57-50 

16.50 

3-83 

0.825 
0.850 

0-875 
0.900 
0.925 
0950 



4572 

'3-72 

16.88 

3.86 



1 

I 

46.72 

14-02    I      3.13 

'7-25 

3.88 



47-72    1 

'4-32    1     3- '5 
14.62    1     3.18 

58-75 

'7-63 

.3-91. 
3-93 

i 





48-72    1 
49-72    1 

60.00 

18.00 

14.92    j 

3.20    j 

! 

1 

1 

'^4 


^^tim- 


Ft 


I'N 


— 


.1 
-t 

-5 

_■! 

5 

S 

5 

y 
■/ 

— t 

■'   i 
\   ! 
_) 
-_< 

— -i 

t 

— \ 

( 
( 

l< 

I( 

t 

1 

I( 
IC 
2C 

2C 

-' 

J 

m 


?< 

Width, 

in 
inches. 

Weight  per 
in  Dound 

foot, 

C 

End 
allow- 
ance 
for  one 
;    bar. 

Rivet- 

Heads. 

1 

1               ' 

__ 

i" 

h" 

i!" 

— _ 

4' 

5" 
6" 

6r 

7' 

7r 

8" 

8]"  ~ 
</ 

9i" 
lo" 
ioi" 
11" 

up" 

12"    "  "  1 

TKR,    IN 
INCHES. 

OF  TWO 
HEADS,  IN 
I'Ol'NDS. 

™~ 

i5 

'•2S 

0.14s 

0-153 
0.161 

i 

o.oS 

__. 

1.36 
1.46 

'     ••57 

1       Tri 

0.12 
0.16 
0.20 

0--5 
0.32 
0.40 
0.47 

— . 

1-95 

—.._ 

— 

0.180 

\h 

I 

"" 

^ 

1.67 
1     1-78 

i      1. 88 

2.aS 

2.21 

2-34 

0.1 88 

. 

2i 
2i 
23 
2i 

2J 

0.197 

~ 

2.97 

3- '3  ; 

3-29 
3-44 

0.215 
0.223 

2.47 
2.60 

H 

— ♦ 

o.2;fi 
0.250   I 

0.258 ; 
0  266 

0.274  ! 
0.2S2  ( 

_t 

12.1''       i 

.3"      i 

•3i"   ; 
'  t' 

14^^ 
ts'      : 

■  sM 

!      I()" 

I 

o-.^5 

-5 

2-73 
2.86 

i         ^? 

1 

.3 

5 

300 

"3-26 

3.f« 

3 

3i 

3l 

3? 

3i 

35 

3^ 

33 

1 

4i 

.1-75    ■ 

3-9«  ; 

*      1 

i 

1 

1 

3y) 

4.06  1 

0.291    , 

-4    : 

1 

4.22  1 

4'"J 

.     - 1 

4.S5    j 
5.00 

5.1(1 

0  299 

iSi" 

"20'          1 
20^"       ! 
21" 

21  r    i 

J 

0.30-  : 

0'3'5  ' 

0.332  1 
0.340^ 

— 1 

1 

-_ 

--  -- 

! 

— 1 

1 

1 

0.34S 

- 

! 

I    ! 


m 


ii^ 


TABLE    OF    LEI 

Weigl 


Approximate  Lengths,  in  Feet,  betw 


TABLE    XXIX. 

TABLE    OF    LENGTHS    OF    LATTICE    OR    LACING    BARS. 

Weight  per  foot  of  same,  and  weight  of  rivet-heads. 


ximate  Lengths,  in  Feet,  between  Centres  of  Rivets. 


TABLE    XXIX 

TABLE    OF    LENGTHS    OF    LATTICE 

Weight  per  foot  of  same,  and  weight  of 

■ 

OR 

rivct-h 

LACING 

ead.s. 

BARS. 

Approximate  Lengths,  in  Feet,  between  Centres  of  Rivets. 

990_ 

009 

031 

11" 

I  Li" 

12" 

1 2  J" 

•3" 

i3V 

14" 

144" 

•5" 

I  c'" 

16" 

i6i" 

17" 

•  7-i" 

18" 

i8i" 

19" 

•9i" 



—     - 

r!o27 



1.119 

1.^38 
1. 157 
1. 180 
1.204 

1.045 
1.065 

1. 08 1 
1. 104 
1. 122 

i.T7"s^ 

•-•95 

1.21S 

"..238" 



- 

1. 214 

074 

t02 

r28" 
153 

1.086 

I. no 

1.230 
1.250 

1.269 
1 .289 

••307 
••327 
'-347 

1.548 

•-587 



'•■45_ 

1. 169 

i-194_ 
1. 219 

••364 

••399 

••135 
1. 160 
1. 187 

1.274 

1.309 

'•383 

1.420 
1.440 

1.456 

'•475, 

••495 

••5^7 

••538 

1.494 
•  •S^4 

1.226 
1.252 

1.261 

1.284 

•-295 
1.320 

'•332 

_i-353_ 

•-.377 

•-367 

r.402 

1.388 

1.426 

1.458 

'-53^ 

••567 

1.602 
1.625 

1.640 

1.678 

1-739 

181 

210 

.240 

.268 

.300' 

■33^ 

■395 
.428 

I  2 1 3" 
1.242 

1.246 

1.270 

Z'^75. 
1.306 

1.312 

••344 

1.414 

1-447 
1.471 
1.494 

1.478 
1.502 

•-553 

1.572 

1.5S8 
1. 610 

1.661 

1.700 

'•774 
••793 

••338' 
1.362 

1.369 

1.404 

'-4,57 

..644 

1 .6S0 

1.720 

•-75S 

1.S30 

1.268 
1.298 
1.329 

1.300 

^■33^ 

••395 

1.428 

••459 
1.485 

■-5'4 

1-527 

••559 

_'-58i_ 
1.610 

1.596 
1.619 
1.644 

1.630  1    1.667 
1.650  1    1.689 

^  ••704 
1.7:5 

•-739 

1.776 

1.814 

1.850 

'•329 
1 .356 
1.388 

••357 
1.388 

1.390 
1.422 

1.422 

'•453 

1.518         1.550 

'•759 

•-795 

•-833 

1.868 

1.450 
'  1-477 

1.480 

i.546_ 

r.5'72 

'-577 

1.679 

1.714 
•-738 

_^749_ 
••77' 

_J:""9_ 
1.S07 

~f.829 

1.S17 

1.851 

1.888 

_'-357.. 

_J-390__ 

J-422  , 

J -453 

1.419 

1.448 

1.509 

1.540 
1.567 

._L-.595_ 
1.623 

1 .650 

1.604 
1.630 
'-657 

'•637 
1.664 

1 .670 

'•704 

1 .840 

_'-'^"7._ 

••_9L3_ 

1.422 
1.450 

1.448 

1.476 

1.506 

••5.16 

'•599 
1.627 
1.652 

1.697 

•  •730 

1.762 

1.786" 

1.811 

••7'i5 

1.864 

1 .900 

1.936 

••477 

1.50C 

•■535 
••565 

••565 
••593 

1.689 

I.7I4_ 

1.742 

••723 

••753 

1.SJI 

1.852 

1.887 

r.923 

1.956 

1.480 

1.509 

••5.3<^ 
1.567 

••599 

1.6S1 

••745 

1.776 

_J.-^-^-_ 

i.8t6 
1.902 
1.928 

1.911 

••935 

1.944 
1.969 

1.978 

•459 

1.485 

1.514 

1.540^ 
•  •572 

••595 
1.627 

•-657 

1.689 

~f.723" 

'-753 
1.786 

_':623_ 
1.652 

"1.681 
1.714 

_J-745 
1.776 
1.811 
1.842 

_l876_ 
1.911 
1.944 

1.680 

1.710 

1.771^ 

1.S05 

•■835 
1.863 

I.iS(i() 
i.,S()5 
'-'J- 5 

2.003 

•494 

1.518 

1.546 

1.680 
1.710 

1.709 

1.740 

1.769 
1.800 

1.801 

1.83. 

1.960 

__L994 

2.028 

.527 

••55° 

__l--577__ 
1.610 

1.604 
••637 

1.630 

1.G64 

_i.697_ 

••730 
1.762 

1.740 

1.770 

i.8?o 

1. 861 

1.892 

1.956 

1.988 

2.023 

2053 

:S59_. 
.596 

f'3o 
.667 

l7_°'L 
•739 

V.584 

1.742 

'•76'; 
i.Soi 

1.800 
1.830 

1.829 
1.859 
1.890 

1.8  sy 
1.889 

1.890 

1. 92 1 

1.951 
1 .9M0 
2.009 

~IK°37l 
2.0(17 

1.9S2 

2.016 
2.042 
2.070 
2.100 

2.046 

2.081 

1.619 
i.650 
1.689 

1.644 

1.670 

1.771 

1.920 

_  1-950  _ 
•-977 

2.013 

2.038 

"2.068 

2.098 

2.1  27 

2.156 

2.187' 

2.219 

2.2.^9 

2.077_ 

2.109 

1.679 

1.704 

1.805 
••835 

1.83, 
1.863 

1. 861 
1.892 

1.920 

1.948 

2.102 
"2.131 

2-133 

_J-7i4_ 
1.749 

•  •73« 

1.921 

1.950 
1.9S0 
2.013 

_L977_ 
2.009 

2.008 
2.037 

2.161 

1.725 

1.77 1 
1.807 
1.840 

1.877 

_l-79S_ 
1.S29 

"T.864~ 
1.900 

1A93'''^ 

_'//'9_ 

2.005 

2.040 

2.076 

~^27n4 

1. 82 1 
1.852 
1.887 

1.869 
1.902 

1.895 
1.928 
1.960 
1.994 
2.028 
2.061 

1.925 
r.956 
1.9S8 
2.022 
"2^053  " 
2.089 
2.122 
2.TT5'" 
2.1S9 
2.225 

••95' 
1.982 

2.016 

2.046 

2.081 

2.115" 

2.129 

2-159 

2.189 

'•7  59 

1-779 
1.8.7 
1.S5. 

2.038 

2.068 

2.01  )S 

2.156 

2.187 

2.219 

776 
.81.) 

'•795 
'•8^,3 

'•935 

_K969 

2.003 

-i037__ 
2.071 
2.106 
2.140 

2.042 

2.070 

2.100 

2. 1 29 

2.186 

2.216 

2.244 

••923 

2.077 

2.102 

2.131 
2.161 
2. 192 

_J;J59 
2.1S9 
2.2.M 

2.216 

2.244 

2.273 

;s5o" 

.886^ 

;02S 

1.868 

1.888 

••9'3 
1.947 

"   1-983 

1.956 

1.978 

2.109 
"2^140 

2-^33 
2.165 

2.244 
2.276 

_---73._ 
2.304 

2-303 

__l-.?05_^ 
1.940 

1.926 

1.990 

2-013 

2-3.33 

1-959 

2.026 
2.060 

2.04S 

2.083' 

2.120 

2.095 
2.129 

2.146 

2:179 

2.214 

^  2.248 

2.172 

2.229 

._."--4 . 
2-257 

2^253 
2.2S4 

2.280 
12.313"^ 

2-,M3 
2-374 

:    18" 

2.308 
1-337., 

__  2.334 
2.364 

^^.-■3(>3_. 

•959^^ 

1-977 

2.034 

2.020 

_Ji!S7.„ 
2.094 

2.206 
2.240 
2.273 

16" 

-•393_ 

2.016 

2.099 

=••34 

2.164 
2.200 

Mi" 

2.264 

2.297" 

2.288    1     2.319 

2.368     !      2.39() 

2.400        2.428 

1 

-•42  5  _ 

ol" 

2.051 

2.070 

2- 153 

2.178 

2-324 

2-319 

2-455 

1 

12'," 

•3" 

•31'" 

■4" 

1  -  "                 »  r  1  " 

i6i" 

.7"      1     '7/' 

1 

iS.i"     1      19" 

,     '9'/' 

. 

1 

Width, 

in 
inches. 

Weight  per  1 
in  pounds 

Foot, 

End 
allow- 
ance 
for  one 
bar. 

Rivet-Heads. 

iSi" 

19" 

•9i" 

20" 

20  V' 

21" 

21.^" 

22" 

1 

DlAME- 
TKR,   IN 
INCHES. 

Weight 

OF  TWO 

IIE.MIS,  IN 

POUNDS. 

o.oS 

i8" 

v 

■h" 

■ill 

4" 

4V' 

5"' 

5i" 

6" 



I-2S 

0.145 

i 



•.36 

0.153 
0.161 

'1 
It', 

0.12 

6i" 



7" 

•  J 

1.46 
••57 

•■95 

5, 

0.16 

0.20 

0.25 

74" 
8" 

9" 

n'" 
9/ 

10" 
lOi" 

O.I  80 

-    ■ 

■    

2 

..67 
1.78 
1. 88 

2.08 
2.21 

0.188 

1.678 

1739 

1.700 

••774_ 
•793 

2i 

0.197 

IS 

I 

a 

0.32 

0.40 

1.720 

I7SS 

1.830 
1.850 

1.867 

1739 

1.776 

1.8 1 4 

1.886 

1.940 

.'•^59 
••977 

2.016 

2.051 

2.070 

^2.094 

2{ 
2? 
2h 

2.34 

2.97 
3.'3 

0.215 
0.223 
0.231 

•759 

••795 

••'^33 

1.868 

1.905 

11" 

2-47 

4t 

0.47 
0.55 

•779 

1.817 

1. 85 1         1.888 

1.926 

•-959 

1.996 

_2.o34_ 
2.057 

Hi" 

12" 

1.807 

1.840 

..877 

••9>3 

1.947 

1. 983 

2.020 

2.60 

I 

1.829 

1.864 

1.900 
r.923 

1.936 

1.969 

2.005 

2.040 

2.076 
2.099 
2.120 
2.140 

2- 134 

2. '53 

2.17S 

2.200 

I2L" 

,.852 

1.887 

1.956 

1.990 

2.026 

2.060 

13" 

2i 

273 
2.86 

3.29 

0.250 

1.876 

1.911 

••935 

1.960 

".'988" 

1.969 
1994 
2.022 

1.978 

2.013 

2.048 
2.071 

2.083 

i3->" 
•4"  " 
~.4i" 

2? 

3-44 

0.258 

1.902 

2.003 
'2.028 

2.037 

2.106 

1.928 

2.061 

2.122 

2.129 
"1.155" 

2.164 

o7 

3-00 

.5  (v^ 

1     ^  ■,r,r. 

•  .c)S6 

2053 

2.089 

2.189 

2.22  s 

■5" 
'5i" 
16" 
"i6.i" 

1.982 

2.016 

2.042 

2.046 
2.077 

2.081 

2.US 

2.146 

'~2Tr72^ 

2.179 

_    2-214 
2.240 

2.248 
2-273 

3 
3i 

! 

1 

3-^3 
3.26 

3.39 

375 
3-91 

1     0.274 
O.2S2 

— 

2.109 

2.140 

2.206 

2.0 1 J 

—  — 

2.038 

2.070 

2.102 
2. 131 

2^33 

2.165 

2.199 

2.229 

__=fS7_ 
2.284 

2.204 

2.29-: 

2.068 

2.100 

2.161 

2.192 

2.224 
2.253 
2.280 

2.2S8 
2.319' 

2.343 
2.368 
2.396 

2-324 
2.349 

_  2.374 
2.400 

72428; 

2-445 

_-4«2 

2.510 

2-543 
2-570 
2. 596 

3\ 
33 



4.06 

0.291 



2.098 

2.129 

2.159 

2.189 

3.221 

nV 

2.127 

2.156 

2.187 

2.219 

2.249 

2.313 

2-337 
2.364 

18" 

4.22 

1    0299 

2.156 

2.1 86 

2.216 

_2.244_ 

2.273 

2^303 

2.276 

2.30S 
2-334 

1 84" 

3i 

' 



2.187 

2. 216 

2.244 

2.304 
2-333 

4-38     ' 

4-54 

4-69 

0.307 

2.219 

2.244 
2.276 

2.273 
=•304 

2.363 

2.393 
2.423 
2.450 
2.47S 
2.509 
2^543 

2.425 

•  9-^' 

20" 

Vo.i" 

21" 

21I"  " 

22" 

3? 
35 
3l 
4 

1 

0.3 '5 

0.323 

2.249 

_-i-333__ 
2^3''3 
2^393 

2^425 
2-455 

i     •91." 

2.362 
2.392 

2.423 
2.452 
2.4S2 

2.392^ 

2.422 

2.450 

2.4-9 

2.510 

20.i" 

2.452 
2.470 

_-:5°9_ 
2.542 
2.570 

211" 

1 

2.280 

2.308 
'2.337 

"-•3f'S  " 

2^334 
2.364 
2.396 

2-3^3 
2-343 

4.S5    ;     0.332 

5.00  :    0.340 

2-374 

j..\oo         2.428 

1 

iS" 

1 

iS.i"     i      19" 

20" 

21" 

22" 

1 

5.16 

'    0.34S 

J: 


H 


^ 


TABLE 
CHA> 
SPAC 

/)  =  (! 
;k'cs  i>f  c 
tiVL'ii.  the 
;o!itaitiinj 

/) 

4" 

6" 

7" 
8" 

9" 
10  ' 

12" 
«5" 


'1 


TABLE    XXX. 

TABLE  OF  SIZES  OF  LATTICE  BARS  FOR 
CHANNELS  OF  VARIOUS  DEPTHS,  AND 
SPACED    AT    VARIOUS    DISTANCES. 

/'  — (k'ptli  of  clKinncl,  ;ui<l  ,/  =  distance  between  inner 
cs  ..f  ciiannels.     If  tlie  value  of  d  lie  between  the  values 

•,rn,  the  size  of  lattice  bars  is  to  be  taken  from  the  column 

i'ltainin^  the  luxt  /aixts/  value  of  (/. 


/> 

4" 
5" 

6" 

7" 
8" 

9" 
10" 
12" 


Sizes  of    Lattice-Bars. 


</=zD       </  =  1.25/?  '  '/  =  '-5^     '/  -  '^S^^  :     "'  '■ 


iD 


\"  ^  'i" 

i"  X  >l" 

k"  X JS" 

V  X  'J" 


A"  x'4" 

{%"  X   2\" 
3"    X  jj" 


J"     X    It" 
\"    X   U" 

1"  =<  >(■' 

1"    X    Ij" 

i'4"x  14" 


X    \\ 
X 


1" 


X  ,r'    i"  X  .f 

X    l|"         }"    X    li" 

V  X  ,r'    i"  X  .4"   j"_^-" 


I"  x_|r 


( 


X    2" 

X   i" 


A'xir  '  A'x  2^"   rt"x  2r 

^"x:i-      ^"x^r'ift"^^ 

■J"    X   zV'         i"    X   21" 


A"x"2i" 


a  I 


t^ 


!• 


^>l' 


TABLE 
NEL! 
AT  V 

I)  -( 
I,m.'s  ot  », 
,ivi'ii,  till 
rniitaiiuii 


n 

4" 

5'_ 
6"' 

7" 
8' 

9' 
10  ■ 
12 ' 
15'' 


!•'■    •         ''-'"'l-' ■'HI  l|l.l,JI|.iJj,i^WBK* 


TABLE    XXXI. 


TABLE  OF  SIZES  OF  LACING-BARS  FOR  CHAN- 
NELS OF  VARIOUS  DEPTHS,  AND  SPACED 
AT   VARIOUS    DISTANCES. 

n  —  (lci)tli  <»t"  i-'haniu'l,  and  </  =  distaiui.'  hftwcL'ii   iniuT 
iiaci's  (if  (.liaiiiicls.      If  the  value  of  li  lie  between  the  values 
Jveii,  the  size  of  UKMiij;-bars  is  to  i)e  taken  from  the  eolunii 
I  containing  the  inxt  /ti/xisf  value  of  </. 


/> 

,/   --:      /) 

Sizes    ol    Latiiifj-Bars. 
,/    :  \.l-^/)      ,/  =  I.5/J      ./=  1.75/^ 

1 

4" 

r  X  iv' 

1"    X    ,!■'    i      1"    X    ,T"         V    X    -'" 

1"   X  :{■ 

5' 
6" 

7" 
8' 

r  X  ,t' 

i'    X  3* 
i"    X   3^* 

xV  X  :r 

i«    X  2" 

r  X  2i» 

^"X2r 

I'/'x-i'  ,  A"x..i- 

^" X 2f  ^'xlir 

A'x.i' 

ll-/  X  -M" 

rV"  X  2f 
r\"x.f 

9" 

lO' 

y  X  -i" 

,Y  X  2i' 
.V,"  X  3" 

A'  X   2f 

r  X  2f" 

Vxa' 

r  X  .•;■• 

r  X  3" 

12" 

15"    '~ 

r  X  J" 
V  X  ^,r 

r  X  ,;r 

i"  X  3i" 

;..  V  ,- 

I 


•^^' 


C/3 

< 

< 

H 


J 

CQ 
< 


K 


a 


« t 


C/3 

< 

< 

H 

o 

J 

< 


:r 


I/. 

C 


■:r.  2 

.E   « 


-I 


^  i  ^  . 

Si 


■-    ;^    rs 


3    ^   >^  c 
-    j:    75    "J 


.E  i  '^  ? 

rr  C  r;  —   ^ 

—  rj  V  *-- 

-c  .j;  C  C    o 

^  \\  T.  >       ■=. 


c 


rt 


j;C 


~    c    —    ~» 

X3      II      X    -      C 


S. 


u 

•• 

<« 

& 

>. 

m 

W 

0 

1/1 
u 

N 


«    t    »»)  ♦'♦Oi  -f'  ^'  n 


lA 


T»^ 


TC'i  *^^  ■•#• '  ^^ 


'/I 


'» 

1 

\ 

"1 

■ 

"1 

«f 

1 

" 

*     •     '  «    ,►    •    «    i 

"I   "■'  O     t>.,  t-.  W5    »    On' 

i       i       .       I       I      )  I 


'1   fO  "1  '•)   f»)   r^  "f 


M  I     j      !     I     ^ 


T^ 


f^i  f*)    f1    rn    r1    '^    r-,    .,.     .f 


"T  •**  •    '"¥•  "*"  11*  ■*»  «iw   — 

I i  I  I  ,  I  I  ! 


t!  f1 


*^  n 


fO  —   -r 


Ssl^  2 


l>.'~!!» 


"**  ''Vi"'V  *U  •**  •**" 


»      »     »     « 


»  1  C  o  :  M  I  >o 


/I 


If 


'i 


-  tu 

-  O 


\ 


E 1 . 

I) 


i 


I 

t 


'K 


'•}  ii 


W 

fc 


cr. 


H       I 


« 


-  -^   -> 


:r.    o 


y    > 


tc 


tr,    -^   j:: 


V      "J 


"1  IxvO 


U  I 

o    « 

1  -^    «    ta 

tr 

■^•^a"={sl< 


«         "i!  r^. 


O    t^ 


t-^;o '  f^  c- 


t-  ■ 

! 

1 

! 

i     I 

"-I 

ft 

— ir> 

t 

o 

» 

J 

T 

IT'  ? 

•  H"^  "^,<  <i  -^i  ■• 


i/"j  'O     ^'"^  'C 


r^  «  i  1^  O  o 


tf} 


t^,  CN    O      -      '1 


fl^o :  ""•  ss 


S;       fc       t       t 


■^  -*-t   «M    . 


o  vo  vo  >:    ~ 


t    »    t    t 


.  L-  L- l^lj. 


-T     LO,  u-1  v£  .>2     ^     ^ 


■V.       c  •/:    c 


»-       !L-  *     ' 


'•    "".  c    o 


! 


w 


l"(irnui 
the  (Iki 


Uia. 


\ 


D.a. 


1^ 


'I 


■ormii 


BRIDGES    OF    CLASS    A. 

l;i^  f   roller   in   inches.      The  first  aiul  last  vertical  liiie; 


ivc 


the  diam'^'i'-"  l»~''nussil)Ie  pressures  on   the  rollers. 


M" 


;,.(V5 
3.85-5 

J.  1595 
4-^4'L^ 


9.11    i 


4- 1.) 
4.4 


^^'L 

>()! 


!l      4.5>«=' 
'       4.v>0- 


4.,S4 
4'1 


6i 
.Si 


5.00OO 


lo" 


_9:63 

10.13 

10.37 
lo.fio 
10.S3 


tt.27 

I.  4S 

I  I  .1  ic ) 

I  r.c» 


12.50 

C5' 


9-47 

<>S4 

10.20 

10.57 

975 

10.13 

10.50 

lO.SS 

10.02 

10.40 
10.67 

10.79 

11.17 

10.28 

11.07 

11.46 

•0.53 
10.78 

10.94 
11.19 

M.45 
1  \.6() 

'1.34 
11.61 
11.87 

11.75 

12.02 

11.02 

12.29 

Il.2f) 

1  >    1  ■» 

12.56 

11.50 

1 1 .92 

'^■.y 

__'--^-... 

ri.72 

12.17 

12.40 

12.62 

•3.07 

II.OI 

1 2.S6 

'3-3- 

IJ.Ki 

[2.(1;, 

1  ',.10 

i,v;i> 

I2.3S 

12.S; 

';v.i3 

13.S0 

!:;._;() 

',)07 

'3-55 

14.04 

12.7.) 

>3-^9 

13.78 

14.27 

13.00 

•3-50 

I  |.0O 

14.50 

28' 


o-').i 


1.56 
1.86 


2(» 
3.20 

378 

4^03 
4.28 

±JiiL 
4.76 

5.00 


2f 

JLt" 
I? 

11" 


Di 


/ 


TABLE    OF    PERMISSIBLE    PRESSU 

I'ormula,    /- =  o.J5V'<7,   where   /-  is  the  pressure  in  tons  per  Hue: 
tiie  diameters,  and  the  upper  and  lower  lines  the  leii-ih  ot   roll 


3-3» 


•54    I 


3-64 


3.'^5 


4.68 

4.-6 
4.S4 

4.<)2 


3-64 

_3^9 

3-77 

4.1 

3-89 

4.2 

4:°'_ 

4.3 

-(  I  1 

4-S 

4,24 


3-95 
i      4-oS  J 
4.IS 

_     4-35  _ 
4.46 

4.56" 

4.66 

4.76 

4.86 

4.96 

4.24 

1    A^^3 

44« 

__4-5L 
4-59 

5-oS 

S-'4_ 


5-4L 

5-5° 


5-30 

5-4' 

J- 5' 

5.6. 

5-7' 

5.S1 
5.91 

6.00 


5'74 

5.sr)_ 

5-97 

6.o8_ 

6.19 

6.40 
6.^0 


D;a. 


6.ig_ 

"6.31 

643 

>55 
6.66 

"678" 

6.S9 


K" 


6.63 


6.76 
"6.89 

7.26 

"7.3'^" 
7.5c 


6.93 

_.  "^f) „ 

7.07 
7.21 

7  OS 

7.4S 

7-5' 
7.(y) 

7. SI 

7.95 

7.62 

.      >S.O(i 

7-75 

8.23 

-  .s- 
8.00 


16' 


8.50 


S.I 


S.( 

H-5 
8.7 

s.s 

().0 

t8" 


TABLE   XXXIV. 

WISSIBLE    PRESSURES    ON    ROLLERS    FOR    BRIDGES    OF    CLASS    A. 

.  „.cssu,..  in  .ons  per  Im.al    inch  „f   roller,  and  ,/  ,l,e  clian,c.cr  „(  roller  in  inches.      The  «>»'  ;'»''  J-'^;"'''^''  '""^ 
.er  lines  the  len-lh  .if  rnller,s.      The  inlern,ecli,ae  spaces  c.ntain  ll.c  pemnss.ble  pressures  on  the  tollers. 


I 


\ 


lf» 


TA\, 

1  Orniuhi 


Dia. 

ii     to" 

-fk 

4'i 

.l--'>- 

■l-l- 

■4-<"> 

t. 

S-oO 

i., 

\s...'^ 

U^ 

.v.K 

; 

_?•■'', 

k 

5'5^, 

/t 

'  _  S'<'i 

ft; 

5- 74 

?-\5 

Da 

in' 

ta\es  of  classes  b  and  c. 


iirniul:i 


roller   in   inches.      The  first  and  last  vertical  linos 


i!K'  i.ianj^j^.   [HMMiiissihlc  [)rcssurcs  on   the   ••oilers. 


iDia. 


ID  a. 


rr r.t 


26" 


27" 


-1-4- 

■I.5V 

4-9i 

-M'    i 
5-53-, 

5-85    I 


10" 


I0.,]4 
10.70 
11.05 

11.7J 


12.04  I 

'-■35   j 
t2.66 

I2.<)()     I 

'.5--5  r 

I  ;,.;•<  I 

I  (.0<) 

Mo 

l.l.(.J 


0.M5 
10.  V) 
10.75 
I  r .  I ;, 

I  I  ..\'! 

ir..S4 

l-M'l 
I  .'.5.' 

I-;. 17 

14.07 
I4-V' 

1 5.^:0 


10.;,  t 

10.72 

11.10         1 

io.7(. 

1  l.lO 

"•55         ' 

11.16    1 

1     II.CKJ         1 

II  >> 

1  1  .i>S 

IJ.41         1 

'  1  -93 

iJ.jS 

1J.S2         1 

12.30 

12.75 

1      •3-2'            ' 

\:M 

1  ■,.  1 ;, 

1    -yCtO                   1 

1  voo 

IMS 

i.i'C          1 

M'34 

'3.^3 

113 1      1 

iUk 

14.1.S 

1  1.(k)           I 

I'v-I') 

1  I-5I 

1 5.0;,        1 

'43' 

1  1-^4 

i;.r        1 

14.(..' 

15.111 

1 5.70        1 

14.1)1 

1  5.47 

1    i().o2  ;    1 

1 ;  _M 

i;.-S 

i(..;,4         1 

1  ^  :;o    , 

II  1.07 

i().65        1 

15.78    1 

16.37 

!     i^-QS    ;     ' 

1.48 

2.40^!; 

2:,s7 

3-67   I 
.(.06  ; 

t4>   ' 
4.Sj    i 

5.19 

.v55    ' 
5.')o 

0.24 


Dia. 


11' 


I  ■>" 
'» 


6.57 
6<)0 

-•54^ 


JS' 


-i' 

1  't " 

-A 


,1 

3r 

-.1 ' 
3i" 


D;a. 


4 


V- 


TABLE    OF    PERMISSIBLE    PRESSURES 

I'ormula.  /  =  c).,:;i  25VV,  whciv  /  is  the  pressure  in  tons  per  1 
'■;<•  dianietcrs,  and  the   ujiper  and   lower  lines  the  len-tli  of  r 


Da. 

10" 

1 1  " 

\2" 

'3 

14" 

•5" 

16" 

I  ~'' 

l^ 

. — 

■ 



1' 

3..,s 
4.13 

4.2« 

.I.4J 

4.56 

4.0(:i 

1  -'1 

!.;,S 

4^51_ 

4.71 

'    4. so 

5. CI 
5.i() 

4-59 

4.7S 
4.96 

5- '3 
5-30 

5.47 
5-f'3 

4.98 
5.  IS 

5-36 

S74 
5.98 
6.20 
6.42 

6.12 

6.51 

■•03__ 

7-^7 

7v4 

7.()7 

6. 

5-79 

6.37 

6.61 
6.85 

_7.07 
^  7.29_ 
7..S0 

7- 

5-37 
5:56^ 
5-75 
_    5.92^ 
6.09 

"  7 

S-99 
6.19 
6.3S 
6.s6 

/ 

6.63 
6.83 
7-03 

7 

"  s 
s 

.\.S2 

■•30 

5.7.S 

6.26 

(•••74 

7.22 

771 

S.|.i 

s 

„  -•'■94_ 
5.06 

viS 

5'57 
5-70 

5-93 
6.0S 
6.22 

6.42 

6.92 

709 
7.26 

7.60 

7-77 

7.91 
S.io 
S.29 

S.p 
S.I.I 
8.S1 

s 

6.5S 
6.74 

_  9 
9 

_;.;,o 

5-^3 

6.36 

6.S9 

7,42 

7-95 

S.48 

11.01 

9 

5.41 

;.'); 

6.50 

7.04 

7.58 

S.I  2 

8.66 

i)..'0 

1) 

;.;:; 

1  i.os 

6.63 

7. IS 

S.29 

S,S4 

'i-,W 

9' 

^cv, 

(i.:!o 

6,76 

7-3- 

7.S() 

S.45 

9.01 

O.vS 

10. 

-74 

1  •■■;-' 

(i.Sc) 

7.46 

S.04 

S.Ol 

<Mil 

n.-(> 

10 

5..S5 

'■■43 
1  1 " 

7.OJ 

7.(0 
13" 

S.iS 

14" 

S.77 

.5" 

y-35 

l()" 

17" 

10 

n.i. 

10" 

IS 

TABLE    XXXV. 
:ble  pressures  on  rollers  for  bridges  of  classes  b  and  c. 

the  pressure  in  tons  per  lineal   inch  of  roller,  and  d  the  diameter  of  roller  in  inches.      The  first  and  la.st  vertical  lines 
>\ver  lines  the  len,i;lh  of  rollers.       The  intermediate  spaces  contain  the  permissible  pressures  on  the  rollers. 


■  5" 

S74 
5-98 
6. 20 

f,.42 

16" 
6.12 

>7" 

7.03_ 

7'^7 

18" 

.9" 

7.57 

20" 

7.66 
'7.97 
8.27  ' 
8. 56 
8.84 
9.11 
9-.l« 

9-f'3 
9.88 

10.60 
10.83^ 
11.05 
11.27 

11.69 

21" 

22" 

=3" 

24" 

25" 

26" 

27" 

28" 

29" 

30" 

Dia. 

i 

) 

0.89 
__7:'7 
1AA_ 

7.70 

8.04    !       S.42 

8.80 
9.16 

9.10 
"9.56 

9^57 

9.96 

10.34 

10.70 

11.05 

_":39 
11.72 

9^95 
10.36 

10.34 
10.76 

10,72 

II.IO 

11.55" 

11.48 
11.95 
12.40 

>i" 

1    'i" 

!     2" 

'       2j" 

i 

6.37 
6.61 

6.85 

7.07 

__7-29 
7.50 

S-37 
8.68 
8.99- 
9.28 
■9.S7 

lO.tl 

8.76 

11.16 

) 

7.85 
8... 3 
8.40 
8.6  s 

__'^:'>'  ' 

9-39 
9.62 

10.07 
"10.28 

9:4i_ 

9.72 
10.02 

9.51 
9.S4 

9.92 
10.61 

10.75 
11.13 

II. 16 
"•55 

11.58 
11.98 

11.99 

) 

12.41 
12.82 
13.21 
13.60 
•3^97 

^  14.33 
14.69 

_  J  5:03 

._i5i7_. 
15.70 

12,84 

) 

6.63 
'    6.83 

7-5' 
__7:J1_ 
"•07 

S.M 

8.0  r 
8.St 

<).0I 

<>:o 

9.  vS 

'  .>.76; 

9.94 

17" 

7.96 

^   ^-'^^ 

S.44 

8.67 

8.89 

9.12 

9-33 

9.S4 

974 

9.94_ 

io.i4_ 

io.;,3 

10.52 

iS" 

10.17 
10.48 
10.78 
11.08 
n.36 

11.49 

"■93_ 

12.30 

12.66 

13.00 

•.3^34 

12.38 

12.75 

i3-'3 
13.48 

'3^S3 
14.18 

13.26 

14.06 

'-M5~ 
14.82 

'5- '9 

'5'55  1 
__15-9_o_i 
16.24 

! 

10.93 
11.21; 
1T.56 
11.86 
12.15 
12.44 
12.72 
12.99 

n.84 
12.19 

12.S5 

I3^i7 
13.48 

) 

7.03 

7.22 

7.41 
7:60" 

777 

7-95 
_  8.I2 

S.29 

845 
8.61 

'  «77^ 
,5' 

_io.3i 
10.60 
10.87 

2\" 

\ 

__77i__ 

^7:9  L 

8.10 

12.04 

'2-35 
12:66 
1 2.96 

'3-25 
13-53 
13.81 

14^09 

'4^35 
14.62 

2|" 
2i"          ■ 

3" 

10.63 
10.88" 
1 1.13 

"•37 
11.60 
11.83 
1 2.06 
12.28" 

) 

11.14 
11.40 
n.66 

11.65 
11.92 
12.19 

I2^4S 

_'3^67 
'3^99 

) 

8.2(J 

8.48 
8.66  " 

9.01 

_>'9 

935 

16" 

^•5> 
14.84 
15.16 

15^47 
i5^78 

'3^78 
14.07 

_'±36_ 
14.65^ 

lli'93_ 
15.20 

I4^3' 
14.62 
14.91 

11.91 

12.15 

12.39 
1 2.63 
12,86 

22" 

to.  50 

12.71 

13.26 

16.02 

16.57 
16.90 
17,22 
"7^54 

1     3J" 

3r " 

3i" 

I 

10.70 
10.91 
II. II 

12.96 

I3'4S 
-J 

13-52 

•3-78 
^•C'3 

'S^So 
15.78 

16.34 

16.07 

16.65 
16.95 

16.37 

28" 

19* 

20" 

21' 

24" 

23" 

26" 

-.-" 
-/ 

29" 

30" 

Dia,     : 

1 
J 

I 


BL 

RIV 


Beari 


\" 


()88* 


57S^ 
094 

(109 
867^ 

1-5 


BLE    X 

RIVET    T 

CLASS 


Beanng-strcsse 

■\" 

ir 

—    -  — 

(.SS' 

0.719'  '  c 

578" 

2.696        1 

2.<X)6          I 

0<)4 

.V-3S_^ 

r^- 

.^505     J 

(lOtJ 

K74      ; 

S67 

4.044    ,  < 

1 125" 


!■•. 


I  156"    ;     I  iSS" 


in 
u 

',ia 

.r 

]  :in' 

I.-'JO" 

n 

6.750    ' 

7  T- 


S.cKi       s,. 


.fl 


( 


•"•  'T-iMitimMil  illllill  T""' 


It. 

u 
U 

a 

I "      i 
J 

1  ■ 

1  i  " 
1" 

1        J 
1  c 

._,J-'. 

1 '.  ' 

.  « 

liliMllM.- 

M'lMKNTS 

IS    I.NCH 

TUNS 

j 

[ 
1 

!   0250* 

V  n 
32 

S  It 
18 

0.344' 

r 
0.375' 

0.406" 

1.219 
1372 
1524 
1.677 

,   o.43»' 

0.469" 

0.381" 

0  3'3'' 

0093 

0.131 
0  I.So 
0  23<)_ 

0.31 1 
0305 

0   '.'It 

0  ()o; 

0  73(1 

o..S,s"5 

1  04() 

°7S0_ 

o.i;3S 
I    '03L_j 
1    '  '25     ! 

;  1 219 

0.844 

0950 
'055 

ribi 

0.938 

1.055 

1 290 
1 524 

l(.4l 

"•75S 

.875 

'  ■•>■;.) 
2. no 

J  032 
1 161 
1.289" 

1 125 
1.266 
1 406 

1547 
1688 
1 .829" 

''969 
2.110 
27250 

2.31)1 
-  xV 

J-3'3  . 
1.477 
1  641 

'  1.805 

1.969 

1    -''33 

1.407 

'■S«3 

>7S8_ 

-i:934_ 

2.110 

1.419 

r.266 

1  548_ 

1677 

1.S05 

"i-934 
2.063 

2.102 

2  32  1 

1.829 
1981 

2.2S6 

T438 

2  500 
2.742 

'•372 

2  286 

'3'2   . 
1  406 
1  500 

1  ;<M 

1  i,\- 

1  477 
I  582 
1687 

1  7' 13 
I  Si,,S 

,     2.2()7 
,     2.401 
1     2625 

2.461 

26.37 
2.8.3 

27S9 

2..>S9 
,vi'M 

TABLE    X: 

RIVET    TA 

CLASS    1 


Bearing-stresses  i 


r 

W" 
0.406" 

1. 219 

1372" 
1 524 

1,6-7 
"  1  .S29 

l.>Si 

2.2S(, 

243S 

2  51)0 
2.74.' 

A" 
O.43.S'' 

i.477_ 
I  641 

'•'r>l''JL. 
2.297 

2625 

27S') 

ii" 
0,469* 

V 

0.500* 

0.531* 

0.563* 

w 

r 

0.625" 

w 

11" 

0.719* 

J' 

j-jys' 

0.594* 

0.656' 

O.c'kSS* 

0.7s 

i-^S 

1.407 

■•5«3 

1.75S   " 

'•'AM 
2.110 
2286 

1.500 
'  I.6S8  ' 

I-S751 

2.'jf.3 

2.350 

2.625 
.2.S13 
3.000 
3.1SS" 

3  375 

•594 

-  L993_ 
2.192 

2-39« 
2.590 

2,789 
2.<>S9 
1.188 

3.586 

r.688        1.782 
1 .899        2.005 
2.no    '    2.227 

2.1  10 

A-344_ 
2.579 
2.813 

3.047 
3.2S1 

3S'<> 
3-750 
3-9X5 
1.210 

i.:(i6 

2.578 
2.836 
3.0',i4 

3.(0) 
3.867  ^ 

41^5 
4,VS3 

.(I'll 

2.6(j6 

2.966 

3.235 

3-505  _ 

.3-774 

4.044 

1  406 

2.461 

'  2.708 
2.954 "" 

3.200 

3-445^ 
3.692 

3-938 

4-430 

2, Si 

'  547 
I  (vSS 

2.321 

_y3i_ 
2.74^ 
2.952 
3.164 

2.450 
2.673 

3-37 

1 .829 

2.895^ 

.3' 17 

3-.340 

3-65 

1  (/«;) 
2.1 10 

2.461 
2  6.?7 
2-813 
2..J89 

3'6| 

.1').] 
4.JI 

2. 2^0 

3-,376        3.563 

3:5«7__|    .V7S6 
3.797     !    4.oaS 

4-313 

4-5S3 

4.S,2 

4.  so 

4.7S 
i;.o6 

\ 


I) 


1 


Ts 


[ 


vS" 


:t 

it 

'1 


3LE  x: 

ilVET    TA 

ASSES    B    . 


Bearing-Stresses 


w 


i 


vS"   j    0.719"    '    0.7; 


•',3 

J-J70 

3-5 

»o 
:  I 

1  _  ^•707_ 
•t-o-H  _ 

\    4-7 '6 

4.9: 

it 

5.054 

5-2; 

;'i 

5-,5"J' 

S.r3; 

■1; 

5.7  2« 

5-9; 

■  1 

6.005 

6.y. 

Ik" 

1. 1 25" 


'3i 


'  III 


'Hi 


i\" 


.156"  ;    i.iS.s"      I, J 19"  i    ,.2-0" 


S.43S 
9-4'A? 


i 
1 

i 

ZZI~ 

I 

— - —   -  -  -    \"~    - 


')757 


ir.ojo       ro.jS4       10.  ;.|.S 


c 
a 

Q 

_r 

u " 

\\" 

i 

1  ■; 
I" 

w 


-i!_li'«M 


!i 


/ 


I  I 

I 


TABLE    XXXV 

RIVET    TABLE. 

CLASSES    B    AND    ( 


Henoing-! 

MOMENTS  i 
IN  IN1.H  i 
TCJNS 


o.ii; 


0.164 


r 

HI 

I  ■' 

■A" 


0.225 


0-^99 
0.389 


0/3 1 7_ 
0.759 

0.')20 
1 .  I  04 
1.311 


i"   i 

,  0.250" 

^Y 

A"      1 
0.313" 

0.344" 

r   1 
0.375" 

Ji" 

0.281" 

0.406" 

1 

0.938  i  1.055 

..,72 

1.2S9 

1.406 

1.758 
1.929 
2.100 
2.281^ 

-•46.M 
2-637 
2.8 1 3 
2.9S9_ 
3.164 

1-523 

1.055  ;  i-is? 

i-3'9 

l-45'_ 
1. 61 2 

':7i.4_ 

\  1. 172 

'■3'9 

1.465 
1. 61 2 

1-759 
_i.905 
2.051 
2.98_ 

2.491 

1.905 

1  1.289 

1.45' 

1.771 

i.930_ 

2.093 

2.256 

2.418 

2.579 
2.740 
2.901 

2.093 

,  '  .406 

1.583 

2.2S1 

__'_-?i3_ 
1 .640 
1.758 

1.875 

•■7'5 
1.S46 

1-978 
2.1 10 

2.474 

2.6()() 

"2.857 

3-047 

1  .'/)2 

2.242 

3-23^ 

J   109            2.374 

2.63.S 

3-428 

Bearing-stresses  in  tons. 


1.64 1 
i.S46_ 

-'.051 

-•.2  5f)_ 

-•.461 

.•.S7I"" 
3.07  6_ 
,v28i_ 
,v486_ 


i  w  . 

i" 
0.500" 

1T» 
hi 

0-531" 

A" 
0-563" 

19" 

12 

r 

iV        H" 

li" 

0.719" 

J" 
0.750" 

ii" 

0.469" 

0-594" 

0.625" 

0.656* 

0.68.S" 

0.781 

1.758 
1.978 

2.,.j8l 

2.418 
2.637 

2.857 

1.87  s 
2.110 

1.988 
2.240 
2.491 
2.740 

2.100 

2.222 

_  2-3-44__ 
2.637 
2.930 
3-223 
3-516 
3.809 
4.101 

4-395 
4.688 

4-98V  " 

5-274 

3-077 
3-585 
_3:692__ 
_3i999„ 
4.306 
4.614 
4.922 
5-230 

2.369 
2.638 
2.902 

"  3-I65  ' 
3.428 
3.691 

3:9j6^^ 
4.220 

4-t84 

2.503 
2.784 
3-063 

3-~34' 
3.619 

3-896 

4-'75 

_3-_2-'3_ 
3-5-16 
3,S(j8 

_4.i.p 

4-5"" 
_4-834 
_5-'5'> 

5-4:9 

• 

2-344 
2.579 

3-370 

3-S16 

3-707 

3.868 

2.8 1 3_ 

3-047 

2.989 

3-238 
3.486 
3-736 
3-985 
4-235 
4-483 

4.044 
4-380 

4.219 

4-395 

4-570 

4.761 

3.070_ 
3.296 
3-516 
3-7.36 

3.281 
.■3;S16; 

3-750 

4. aw 

4.716 
5-054 
5-39' 
5.728 

4.921 
5-273 
_S-62S__ 
5-977 
6-328 

5-i2( 
S-4<),1 

4-454 

4-733 
5.01 1 

5.86c 

6.22f 

3-955 

4.748 

5-538 

5.801 

6.065 

6.59? 

^ABLE    XXXVII. 

RIVET    TABLE. 

CLASSES    B    AND    C. 


Bearing-stresses  in  tons. 

Diameters. 

i    w 

u"  :   r 

M" 

W 
0.813" 

II" 
0.844" 

*" 

2  0'/ 

0.906" 

w 



0.938" 

w 

1" 

1. 000" 

i^V 

•1^" 

^iV 

«l" 

I  .1  » 
'52 

•A" 
1. 1 88" 

-^"    1    T 

0.68S" 

0.719"  0.750" 

—. : 1 

0.781" 

0.875" 

0.969" 

1.031" 

1.063" 

1.094" 

r.125" 

I.I  56" 

1. 219" 

1.250"  , 

a" 

"  r 
-  J. 

H" 
i" 

If 

3-2^3 
3-5l6 

• 



J-37„o__ 

3-5>6 







- 

3-707 

3.868 

._4-39S_ 

5.126 

5-493 
5.860 
6.226 
6.592" 

4-570 

4-95' 

5-33' 

5-713 
6.094 



1                      i 
'                      1 

4.044 

4.219 

_4-747^_^ 
5.142 

_  5-537^ 
5-933 
6.329 

4-923 

6.358 

6.812 



_4-"P__ 

4:38o_ 

_±570_ 
4.921 

5-273 

_  .S;333  _ 
5743 

5-948 
6.373 
6.797 

7.222 

7.647 

6-153 

-  ^''WJ^ 

7.031 

7.47' 



4-5" 
.  _4-834__ 

4716 
5-054 

6.562 
7-031 

7.500 



i 

6.153 

6.563 

6.973 
7-3^3 

8.J04 

5-' 56 

5-391        5.625 

7.266 

7-735 

7.969 

8.438 
8.966 
9-493 

-- 

5-479 

5.728 

5-977 
6.328 

6.475 
6.856 

_.'^7_25 
7.120 

7.720 

7.969 

8.438" 

S.219 
8.702" 

8-3.^,6 
S.967 

8.7 1 7 

9.757 

i 

5.801 

t 

6.065 

7.910 

8.174 

9.229 

10.020 

10.28.J 

10.5^8  i 

I 


\ 


r\ 


'Hi 


12 


10' 


('0' 


.So' 


100' 

1  lo'" 


l-'O' 


1-0' 

I  So' 


lip' 


RoaJwaj 


Hi 


•(O- 


•So' 


i 


^^^ 


/ 


bpan 


I 


0 


50' 

<)0' 


So' 


100' 


IJO' 


l-o' 
i.'Sr' 
190' 


::.)o' 


-TO 
JOO' 


TABLE  XXXVlll. 

LABOR      IN      ERECTION. 


do' 
70' 

So' 

i;o' 

100' 

I  10'^ 

I  Jo' " 

I  ;o' 
I  ro' 
ii«i' 
1-0' 
l,V' 
uyV 

-M '.  ' 

.'|o' 


-•V/ 
W' 


104 


I  I 

no 

.•S4 


I  IS 

'  I - 

170 

-0.1 

-,V' 

.  vi  5 

.v.) 
-1". 

310 
5  ^" 


r  ;o 

I. So 

-I ; 
.•50 

. » '  5 
.!"> 
-110 

540 

650 

"10 

770 
8.50 

S»IO 


IP 

KV) 

'0 

\<i(') 

11)0 

200 

-v;" 

239 

J()4 

2;S 

^ot 

1 '  7 

.'■} ' 

.>5' ' 

.i~  'I 

.i'i5 

Jir 

■i  >■  < 

404 

^        4^^ 

5'7 

544 

"0 

f^iOO 

(ij ', 

USll 

7-- 

■fi 

7S,S 

■^13 

S;(, 

S-i) 

<)22 

040 

(jno 

I  if, 

JIO 

-'^1 


■115 

57' 


MM 

<  It  r-) 
io.;o 


r 


j  = 


I 


Table! 

TONS    OF 

^'"g-strcss,  J  i„ 


I-engtl 


lor 


Ml/^l  JO.OJ 


A 


-<)-\: 


,,)       ->^-A-, 


I 


TABLE   XXXI) 

TABLE    OF    WORKING-STRESSES.    IN    TONS    OF    2000    POL 


Calculate!  by  the  fumu.Ia/'^       ''''''-^y  wla-rc  /'  is  c.|„;.l  l„  Hk-  w<.il<i„K.stro.ss.  J  tho  area  in 


I  -f  U.004 


D    I 


y;!* 


1 

i        I.lMlgtll 
1 

1.10 

1  .<ir 

4 

4i 

.t.,,s 

5" 

5i" 

0" 

14.10 

7" 
_I7^42 

7i" 
21.24 

25-3H 

8i" 
29.90 

9" 
34.79 

9i" 
40.05 

10" 
45.f'<'' 

:    loj" 

5i.fi.f 

II" 
57.96 

I.J" 
64.64 

12" 

v^   1 

,',.02 

'<■}' 

..«-53 

II. ir 

71.6c 

'•74 

4.14 

j.iSli 

7^95 

10.43 

'330 

|6.5() 

20.20 

24.34 

3S.65 

33-4« 

lS.6i 

44- 11 

50.02 

5<J.27 

62.87 

(h),S2 

••59  „ 

1  j(-. 

3'55 

3-83 

5.07 

.  7.45 
'1.95 

«>8o 
9.21 

•-••55 
n.S4  " 

iS.fxj 
14..SO 

19.32 

I.S.27^ 

33.07 

_  27.44 

26.2(> 

32.12 

3.1.S4  "^ 

37^^8 
35.79 

43.62 

41.13 

48.42 
46.83 

54J9 
53.90 

61.10 
59-33 

67.97 
66.15 

o.;(i 

'  ■ '  • 

-•'"  _. 

3.2.1 

4'7.5 

(>.5i 

.*<.(.5 

1 1.17 

14.07 

'7^37 

21.05 

25^'3 

29.51) 

34.43 

3().66 

'    45^2f> 

49.59 
47.W 

57.58 

6|.2S 

1       1  1 

o.;o 
0.64 

1,1  1 

2,01 
l.M. 

3.01 1 

2.S5 

4.41 
|I3_ 

li.lO 

5.72 

.S.14 
7.(i() 

'^^•55 

'1-97 

•334 

ij.i.l 

10.51 

'  .S-70 

1    20.0S 

34.03 

32.1)1) 

!    2.S..]S 

.IV  •' 

4.V72 
42.22 

5S.''<4 
54.13 

6...45 
(0.64 

0.-,i) 

1.7.1 

.v^>7 

.SvV^ 

/  •-•* 

.1.42 

M..|.) 

'4.y3. 

lS.3() 

3I.(>S 

,    26.04 

30^59 

35.48 

.10.75 

46.42 

5-'.45 

58.S6 

1     J 

0.;; 

0..).  p 

1  .(ij 

2..1.S 

•,.t<2 

5.05 

(i.Si 

S.I  II 

1      II.3.S 

14.21 

17.43 

31.03 

25-01 

29^39 

3416 

.i9.3- 

44.87 

j    50.80 

1    57." 

0.51 

0.1)2 

1.51 

-■,V) 

.v.V.) 

4-75 

'M3. 

S.44 

i_l0.79 

'3^52 

16.62 

30.11 

2.V<>S 

2S.25 

32..S() 

37^9't 

43.37 

49.19 

SS.58 

i       ; 

0.4S 

0.S5 

I..1I 

2.I.S 

.^I9 

4.4S 

().0S 

7.W 

1    10.26 

13..S7 

I5.S() 

«).24 

22Sy.) 

27.14 

3'-('7 

3''^5') 

41.91 

47.61 

53.70 

'  OJ 

-^.-if  _ 

o.Sc 

1 ,;,.' 

2.0; 

j.Ol 

4-2,? 

5--'-> 

7  •5''^ 

'>74 

12.27 

\    '  .V  '  5 

I.S.tl 

22.05 

36.07 

30.49 

1    35^30 

40.49 

46.08 

52.05 

1    1 

0.42 

0.75 

1.2-1 

li»2 

2.,S3 

3'W 

5'44 

7.19 

9.27 

ll.(K) 

'4.47 

17.(1. 

21. 1? 

25.06 

2')..V' 

,    .Vt'O.) 

39. '2 

4.|.59 

SO-4  5 

I        ;     '. 

0.39 

0.70 

'•'7 

I.Sl 

2.07 

3-78 

5.16 

(1..S3 

«.82 

11.15 

;  •3^.\? 

Ki.SS 

20.29 

24.09 

28...7 

1     ,i2.8.1 

37.79 

•y.'4 

!    -iS.,SS 

'3 

J?-.37_^ 

O.fiT) 

I.IO 

'•7  1 

-■.''.1 

3-5« 

4  •■*<■) 

-.4'! 

S.40 

10.(14 

'     '3^22 

l(..|l> 

I'M" 

33.16 

27,22 

31.68 

•  3''.  52 

1    4^.75 

47..17 

1 ; ', ' 

o-.H 

0.02 

I.C4 

r .( i2 

-■.]'> 

.i-39 

4"t 

(.  iS 

.S.OI 

10.17 

12.65 
13.11 

1  S.49 

IS.70 

-I  t    -n 

26.26 

■?0.  t!6 
-■9.47 
2S.45 

35.28 
,54.0s 

32.93 

40..W 
39.08 
37.82 

45-.^9  ■ 

4.1.47 

43.0S 

10'       ' 

0.32 

0,59 

0.()S 

'•5.5 

2-27 

3-22 

4..I2 

.,ss 

7.<->4 

9-7  • 

14.85 

17^95 

2':,.2U 

i(-.l' 

0.30 

^-?',5S_ 

o-T, 

i|5 

-•'.^ 

",.0() 

.1.20 

r.iKi 

7.29 

9.2.) 

II. ro 

14.2.) 

17.24 

20.()0 

24^.?4 

1 7 

0.21) 

0.52 

O.S.S 

'•,57 

J.Cl 

2.1)1 

;,.9S 

^  ,\^ 

(i.i)(i 

S..SS 

11.11 

i.5''7 

'"•57 

I9..S3 

2.V4''> 

27^45 

31..S4 

3f'.59 

41.75 

I     '"!' 

0.27 

0.50 

0..S3 

1 .;,(.) 

I'M 

-'•77 

;,S, 

:.IO 

(.(.; 

S.50 

10.65 

13.12 

•5^93 

1 9.09 

22.61 

26.50 

30.77 

35-4  • 

40.45 

1       iS' 

0.20 

0.4; 

0.-9 

1.24 

I..S3 

.  -•''■•__ 

.v''4 

1"''7 

(1  ;() 

S.I  5 

10.21 

1  2.60 

1 5.32 

..S.,!.S 

21.S1 

25^59 

29-75 

,34.28 

.59.20 

'    J^il 

0.25 

0-45 

0-75 

i.iS 

1.76 

-■•52 

.v47 

1.1.1. 

(..10 

7.. So 

i).So 

12.11 

'474 

17.71 

21.04 

24.72 

2.S.76 

3,?. '9 

37-99 

1     M 

C.23 

0.4.1 

0.71 

1.12 

\.(>S 

2..|0 

.V.?2 

|.|(, 

S.S4 

7-J9 

9.41 

11.64 

14.19 

17.07 

20.29 

23.88 

27.82 

.32.13 

36.82 

\n\ 

0.22 

0.41 

0.<vS 

r.o; 

1.(0 

2.29 

;,.i.S 

127 

S.()0 

7.  IS 

9-05 

11.20 

•3'''7 

l(..4(. 

i().i;i) 

23.07 

26.91 

31.12 

35-70 

0.21 

_o^y) 

0.65 

1.02 

••53 

2.19 

3-04 

1.09 

5^3S 

6.t/j 

8.70 

10.78 

•3'^7 

1  5..SS 

iS.ijj 

22.50 

26.04 

.50.15 

,54.61 

,      joV 

0.20 

0.  ■;- 

0.(t2 

O.yiS 

i..|(. 

2.10 

2.91 

v<)2 

5.1(1 

( ..( .2 

S.V' 

10.  vS 

I2.(..) 

1  5.32 

1S.27 

21.56 

25.21 

21J.20 

33-57 

1      -:i 

'Jv).> 

0.59 

0.> )] 

1.40 

2.01 

2. So 

>■ .  / 

4'i> 

''■.i7 

S.05 

10.00 

12.24 

i4-7'» 

1 7. (.5 

20.86 

24.40 

28..30 

.32.56 

°A~^^ 

0.57 

0.S9 

■•.U 

1.92 

2.(l.S 

;.l.2 

4.7(. 

"•13 

/•75 

9.64 

il.Si 

11...-S 

17.0(1 

20.18 

23.<'3 

27.42 

3 '-59 

'      ■'  -' 

C.^,2 

O.-yl 

O.S( ) 

1.29 

I.S5 

•^•57 

.5-47 

4-57 

5.IJ0 

7-47 

9.29 

1  l..|0 

i.'v7') 

lf..^O 

").53 

22..SS 

26.51) 

,30.65 

i      jJl 

0.52 

O.Sj 

1.24 

I.7S 

2.47 

"v34 

4.41 

V<H) 

7.20 

.S.i), 

1  I.OI 

i.v.i.; 

1  ;.i)() 

iS.()o 

22.  IS 

25-7') 

29-75 

-     1                      ! 

0.50 

0.79 

l.lS 

r.71 

2-37 

1    f  1 

4.24 

5'I7 

(1.1)4 

S.(,5 

io.(.;, 

I2.,S.| 

1  5.44 

1S.51 

21.49 

25.02 

2S.SS 

-.U'  f! 

0.4.S 

o.7() 

1.14 

1.04 

^-•-9 

v09 

4-0.) 

5.^0 

(1.70 

S.V- 

10.27 

1  2.47 

'4^').i 

'7.7t     1 

20.S4 

-4  ,57 

28.05 

^4'     H 

0.4() 

0.73  _ 

1.09 

I.5S 

2.20 

2.99 

3^'>.^ 

5.10 

().4() 

S.oS 

'i-'i.i 

12.06 

'4-17 

17.19     j 

20.21 

2.5^55 

27.24 

1      -5 

■---    -  - 

0.70 

o.()5 



1 .05  _ 

I.OI 

o.9,S__ 

o.(»4 

0.91 

o..S,S 

0.S5 

I.S2 

'•47    ' 

I.41 

..36 

i.,;2 

1.27 

'•23 
1.19 
1.15 

.2. 1  2 

2.05 
1.97 
i.<p 
1.84 
..7.S 

t.6() 
1.6 1 

^  -••^7__ 
-•/  7 
.MkS 
2.5S 
J.  50 
J.42 
-•■>.> 

2.2() 
2.19 

VSo 
'"^•f'5 

3^.=;4 

3^4- 

3.20 

.v'O  _ 

3.0U 

2.</) 

l.'i-- 

4-,';'> 

^4.21) 
4.15 
4.02 

;,.S9 

(1.25 

(>.0.| 

'"  5.S4 
S.(.5 
.S-47 
5.29 
5.12 

4^'>7 
4. Si 

7. Si 

7'55 
7., 30 
7.06 
(..S4 
6.63 
6.42 

(..04 

i).(.i 

9.00 

'  •'^•71 

S.4.1 
S.lS 

7.')4 
7.(«) 

7^t7 

11.67 
11.51 

IO-9.S 
IO.(.l 
10. 21) 
10.00 
().(.S 

<»-.i9 
().I2 

1-1.02 

i;,.'io 
'3' '7 
12.77 
i2.;,i) 
1  2.02 
1  1.07 

"•3.1 
1 1.00 

i(i.(.6 
16.15 
1  5.67" 

15.20     i 
14.7(1     1 
'4,53     i 

1 5.112   : 
1.5.52    ' 
'.(•'I 

19.60 

19.02 

"lS.47 

'7-93 
17.41 

ll).92 

l(..14 
15.119 

1  vvl 

--•''*7__ 

21.57 

20..)5 

20. 56 
I9.-I) 

19.25 

'■^•73 
iS. 22 

2(i..|6 

^sr  ! 

24.99 

1!   ^rr' 

-      - — 

2  1-,;<:' 

■   -'r  -t 

-3-6.5 

- ,' 

— 

22.1)9 

22.,56 

" 

— 

, 

2  1 .76 
21. iS 

J,   -'^, 

Ml 

..5f. 

J.  I  2 

2..SI 

;,.(.(. 

4.()7 

5.S(, 

7  •  2 .5 

S.S3 

10.70 

'2.-7     1 

Ivl2 

'773 

20  (.2 

" 

.    -—  - 

.._ 

^ — 

•■5' 

1..16 

1.12 

2.05 
1 .99 

'  -93 

2.72 

-•57 

341 

4^53 

4.40 

l-'7 

5.6IJ 

5^S-' 
5^.v 

7.04 
6.S.1     j 
i,.(,5     1 

S6j 
,S.5(, 
•^■'3 

10. 41) 

10. 1 1 
').^3    , 

12.42     1 
12.10     1 
11.7..     1 

14.71     _ 
'  1.50 

'  3-VI3 

17.25 
i6.,So 
i(>.;,(i     ! 

2O.0S 
IV-S7 

■ 

|i).0(l 



-  — - 

'•37 

1.S7 
'•77 

2.4<) 

2.42 

-•35 

v24 
.V'S 
^•o() 

4.15 

_4-03 
;v92 

5^2 1 

5.117 

49.? 

6.46    j 
(1.2S     i 
6.11 

7'')i 
7-'") 
7.4.S 

<).57 
9.31 
9.0(1 

11.44 

11.14 

lo.S-i 

'3-.S« 
'.)•-'     I 
i  2.,S8 

JS^94 
'.S.r5 
15.14     I 

i,S.5S 
iS.ii 
1767 

' 

- ^ 

- 

'•7'  _ 

* 

2.2S 

2.16 
2.10 

2..>S 
2.S.) 

2.Sr 

2-7  1 

VSi 
.v70 

,v''0 

4'7') 
4.1.(1 

(•54 

|.|2 

.S-79 
5.64 

5^4') 

7.29 
7.C9 
6.1)1 

(^■•73 

S.S2 

S.5.) 

'^•37 
S.I  6 

1 0. 5 1 
10.  .50     1 
10.04     1 
9- 7  9     1 

12.54 
12.2,5 
1  1 .92 
1  1 .65 

14-76     j 

'4-.5y    1 
14.04 

i,5.(xj 

17.22 

l(i..So 

i().40 
16.00 

^ 

I       13i'""i 





1    M''  ' 



" 



2.0.1 

-'■'17 
2.10 

'v\- 

3^,15 

(•,ii 
.1.19 

.v3.^ 
S.21 

6.:(. 
6..10      j 

7^'»6     I 
7-7''     ' 

9.55 
9.5'      1 

'  '  31       ! 

1 1 .07     1 

'3^.5'' 
'3^o5 

1  5.02 
15.25 

1    1-' 

1       x-V" 

. _ 

-•.VI 
2.\U 

1-24 

;,.Mi     i 

.1.09 
.V'»S 

4.97  ! 

(..24      1 
(.oS      ] 

7-^7        ; 

7-.v'^ 

i).09 

.N.S7       . 

1  o.So     i 
10.155     j 

12.74 
12.41      I 

14.S9 
'I-.S5 

l      5./ 

1 

-    ., 

voS 

;.i)o 

4^>i.5      { 

.v')|      i 

7.-I 

S.(j() 

1 0. 50     1 

12.15     1 

14.22 

1   V   ■ 

;.oo 

.V79 

4-~2 

y~') 

7-o; 

■"^•4.^     ■ 

lO.Od 

11. S7     1 

'  3-89 

2.93 

3^70     1 

l.(«   1 

.vO.S      1 

(,.S7 

S..'(. 

.;.S,5      , 

1 1 .60     1 

'.5-.t8 

i 

1 

;    -    

.  ___. 

2.'.()      i 

,v'"      ! 

1 

■;•.•■)   1 

(171 

(.,;;; 

S.Od 

7.SS     \ 

9.r«D 
9.. 59    i 

"•.54 
1 1.09 

'327 
'3' 2 

1  "W^" 

-  j' 

,M  1 

l..'S 

"i  ■  -  7 

II.  tw 

7.70 

.).iS 

1 0.S4 

1 2  70 

i 

.V  V'        < 

i-i'i    1 

.V '  5     i 

(..21. 

7-5.) 

S.97 

10.(0     i 

'243 

rjA' 

1"' 

1 

! 

' 

.|.09 

.vC.>       1 

().12        ; 

7^,V.     1 

S.7S 

10.57 

12. H) 

ABLE   XXXiX. 

)NS    OF    2000    POUNDS,    FOR    SQUARE  WOODEN    PILLARS. 

K-strcss.  A  ll.c  a.va  in  a  imlu's.  /.  tlu-  I.„^th  in  inches,  and  JJ  the  length  ni  side  <.f  s.marc  in  incncs 


f 


\ 


TAE 


I 


Len^ 


I 

(> 
s 

lo 
I ..' 

I  1 

III 
IS 


^      Bit 


TABUD    AS    STRUTS     IN     LATERAL 


l\ 


Length 
in   I 


.,'  loH  J 


s#i. 


1 

(, 
s 

10 

I  J 

M 

III 
iS 


-•■) 
Ji'i 

-•S 


to 


MDK- 
WAV*. 


I  1..' 
<).-' 

7-4 
6.0 

S-o 
.».o 

-•5 

2.0 

'•7 
••5 
'•,1 
I.I 

o.<r 

o.S 
o.S 
0.7 
o.r. 


KiK.K 
WAVH 

IV-' 

I  ',.0 


'■^•7   1 1 ; 

I'.e     I! 


iri. 

13.3 

I  I .() 
I  1.0 
10.5 
1 0.0 

''•5 

,s.,s 

_S.3 
"7.7 

6.7 

(>.0 

5.(1 
5.0 


.SlDR- 
WAV*. 


lo.S^ 

lO.J 

l).0 

7-t 
S-9 
4.S 

.|.0 

2.0 
I.S 

1.6 
1.4 
t.2 

1.0 

o.y 
0.8 
0.7 
0.6 
0.6 
o.; 


KlXiR. 
WAVH. 

io.8_ 

lO.f) 

10.) 
lO.J 

10.0 

7  9.8 

s.s 


Length  of    Strut 
in    feet. 


n  i)     ®  ® 


10 

12 
It 


5.S 

.v.> 

"5.0 

4.8 

4.3 
4.0 


.50 




1.5 

1 

',.0 

t-5 

().G 

3 

3 

4 

<).o            C) 

10., 

7   1 

'    »4    I 

(6 

8.0  ^ 

r8 

7-5 

20 

7'0 

22 

6.6 

34 

6.2  :i   26 

12 

'5-0 


1 

32 

34 

; 

36 

3« 

1 

40 

16.5 

1. 

18.0 

12 

H)S 

'3 

21.0 

't 

22.  , 

'5 

24.0 

16 

25-5 

t7 

27.0 

«8 

2S.5 

JO.O 


.i9. 
20 


1 

■ 

I^HK^HDI^HH 

TABLE     OF    APPROXIMATE    WOR 


1 

L 

ength  of    S 
in    feet. 

trut 

7"  20# 

!• 

7"    l'^#  I- 

f~\ 

f 

SlIIK- 

F.IH.K- 

SlDK- 

Ki)(;e-     I     Si 

. 

\^ 

■.^    v^ 

\S   \\s. 

«  \v^. 

»  W-. 

WAYS.              w 

- 

=^- 

- 

^.   _ 

1 1  '"" 

I 

-''•7 

27.0  1 

24.2 

24.5      M       2 

•y 

'■5 

1 

JIl.t 

26.9 

-'-1-0 

2.}..( 

1 

vO 

-' 

-\vO        . 

26.7 

22.7 

-I'.l 

(. 

■'•'_ 

■5^" 

23.0 

26.S 

21.0 

24. J                 1 

s 

(i.e. 

I 

20.^ 

26.2 

1S.7 

2.|.0               1 

10 

7*5 

5 

I.S..' 

26.0 

16.5 

^,v7             1 

12 

0.0 

('. 

'5-7     ^ 

-5-7 

'1 

i-t.5 

_  2;,.5           1 

1  I 

'°i_ 

/ 

_'3-7  _; 

25.2 

..^'-•5_ 

23.1            1 

1 1 

1  J.O 

,s 

r2.o 

2.1.7 

1 1.2 

■>  >   — 

|S 

1  ',.; 

t) 

10.3 

2-1.2      1 

')■: 

■>->■* 

'  J 

''>'^ 

10 

->o 

23-7 

,S.s 

^!''i  — 

i  * 

10.5 

1 1 

s.o  ; 

23.0 

7-  > 

1           "■• 

iS.c 

1 J 

7.0 

--■.1 

(..5 

'o-i:2  z 

i'>5 

21.0 

i  1 
1 1 

(i.j 

21.7 

-M.l 

>•  / 
'^.a 

20.2 

j.> 

i<).^ 

V- 

15 

16 

'■0 

20.5 

4i 

1.S.7  ^, 

.t.o 

I  s.o 

^  * 

-5'.> 

17 

(.0 

li|.2 

.V  ^ 

'7-i       . 

■,l) 

27. c 

I.S 

.  '-^ 

IS.I, 

"v- 

170 

;^ 

.•S.5 

10 

.V-: 

I.S.O 

vO 

II  1.3           :      __ 

10 

.lO'O 

20 

.vO 

'".74      i 

27 

16.0 

TABLE  XL. 

PROXIMATE    WORKING     LOADS     FOR     I-BEAMS     USED    AS    STRUTS    IN     LATERAL 

SYSTEMS    OR    SWAY    BRACING. 


20#  I. 

7"  iS#  I- 

()■'  II* 

I 

;       6"  ..; 

i 

5#I      1 

1 

#i. 

5"  'o*  I. 

j! 

1"  io»  I. 

4"  8#  1- 

i 

1 

Length  of   Strut 
in    feet. 

F.DC.K- 
wws. 

SlDK- 
W.WS. 

24.2 
24.0 

22.7 

21.0 

Kni-.E-    .  1 

WAYS. 

^""347^1 
24.4  J  1 

24.2    ' 

SlI.K-       j 
WAYS.      i 

21.2 

20.0 

I, So 

1 5.S 
'3-7 
"■7 

IOC 

S.7 

7  ■  ^ 
(.., 

___S-7 

)•-' 
3  7 
3-? 
]■[• 

■J  "i 

■»  1 

2.0 

KlM.R- 
U  AVS. 

21.6 
Ji.S 

J  1  .2 

:i  0 
J0.7  _ 
JO.  2 
i'i-7 

t'l-2 

I  S.7"" 
iS.l 

i-.o 
II.  : 
i  v5 
1  i.o 

||  =; 

1  (0 

130 
IJ.3 

SmK- 

W.WS. 

KiHM.:- 

VVAYS 

18.2 

i8.r 

18.0  " 
17.9 

'7-7 

'7.5 
17.1 

SlDl-;. 
WA\s. 

16.0 

'37 
1 1.7 

97 
8.0 

Kdc.e- 

WAVS. 

[6.0 

SlllE-       '       EUGE- 
'       WAYS.      j        WAYS. 

SlDK-       1       F.IK.E-       ' 

Side- 
ways. 

Edge-    i 

WAYS. 

mm 

413  ® 

®  9 

27.0 

18.2 

'7-7 
.fi.s 
1  5.0 

'3-- 

i_  "■s„ 

9.2 
8.0 
6.7" 

i      5.O. 
4.S 

4.0 

3-5 
3> 

-•7. 

2.0 
1.7 

13.8 

,3.8 

'J-5         '.V5 

!-•"            1 3--' 
11,.:          13.0 

10.8 

10.8 

I 

26.9 
26.7 

LS-9. 

'57 

11. 1 

1     9.7 

13.0 
12.8 

10.2 
"9.0 

10.6    i 
"10.4    ; 

2 
"  "4 

6 

„._'-5. 
3-0 

I 

2 

26.5" 

'5-5 
14.9 

12.6 

9.2    '\      12.7 

74 

10.2 

4.5 

3 

2(1.2 

^lS.7  "1       24.0 
16.5           2;,.7 

i     8.1    :     .2,4 

74    ■      i^o     I       S'9 

1 0.0 
9.8 

8 

6.0 

4 

2f).0 

6.7        12.2 

6.0    j      12.2 

"5^       11.6' 

4.0          1 1 .0 

3-          'O'S.J 
j.S          10.0 

4.8 

10 

7-5 

5 

'       ^v" 

1 1.2 

-3-' 

65 

54 
4.4 

'  ^3-6 

3-0 

14-5 
14.0 

I.VS 

'3-0  ^ 

._  ■-•5 
12.0 

II. s 

i       54 

\  -    37.  _. 
3'0 

12.0 

~ri.7" 

4.0 

.^2 

9-3 

12 

9.0 

6 

""'       2^2     ' 

.6.7 
16.2 

'S-7_; 

•5-2 

8.8 

14 
16 
18 

10.S 

7 

~'-    '  2:1.7  ■■ 

"•3 

10.8 

10.4 

2'S 

8.4 

12.0 

8 

9 
10 
II 

-4- 

().;                32.2 
7.5      !        21.2       1 

■y-      '        20.2 

4.S            1.S.7 
4.0            iS.o 
.;.;          17.; 

2.0 

8.0    I 

'3-5 

-V7 

^^    2-5 

!       2.2 

1    2.0 

-•-     ,       9-5     ,       '•» 

7-5 

20 

15.0 

-3-0  , 

.4.7__ 
14.2 

13-7 

_  '-_-Z__ 

I  2.2 

2.6 

2..5 

1       2.0 
1.8 

1 0.0 

9:6 
9.2 

\S.7" 
S.I 

2.0   :     8.8  j 

,       ..6 

7.0 
6.6 

22 

16.5 

1 .-             S.2     1 

..;  .-77- 

1-3           7-2 
>■'     i       6.7 
0.1)    '       6.3 
0.S     j       6.0 
0..S  '        5.6 
■7  '0.7;          5--  _ 

O.h               5.0 

;  .4 

24 

18.0 

12 

1 1.0 
10.4 

')7 
y.o 
8.2 

7-5 

1    1.6 
'•5 

1.2 

6.2 

26 

__'9-.S_ 
21.0 

'3 

'  1     I 

I.O 

5-8 

28 

14 

'^O  ^       ' 

1 .6 
1.4 

1.0 

o.y 

'      0.9           5-3 

30 

^  22.5 
24.0 

'5 

''■3    1       7-'5 

1       I.I     1       6.8 

1 0    I       6.2 

0.8            5.0 
1      °7         J.:S„_ 
0.6           4-5 
0.6           4.2 

32 

16 

34 

25-5 

17 

11.7 

ri.2 

10.7 
10.2 

>                 H)- 

36 

27.0 

18 

.]•-          '"" 

16.0 

C.7 

'9 

^     :      18.0 

!       3-0 

i       ^-7 

■          O.f) 

38 

j     30.0 

0.8    1        5. 1 

'    0.5 

4.0 

40 

20 

>     '      174 

Ml 


Twp  <    llol 


h.'ll.im  ( 


li.ittc  I  l;i.i 
Diagonal 


I'ovl  criiin 


I       I'ciSl    (DihIs 


'RUSSES. 


tv 

\' 

\ 

\ 

\^ 

\ 

{       4 

\ 

\ 

\ 

e    \ 

\ 

\ 

\ 

\ 

\ 

: J . J 

\ 

\ 

8  Panel. 


Memi' 


Tuii  ri„.r.l 


IV, 


"       i     8 


6 

_ri 

8 


9  Panel. 


w 


Multiply  by 


W'. 


I'.'-iioiii  (  ii,,i       J.J  ji 

"I      3i  Ji 


"  " ;     6 


7 

9 

') 

10 

10 

10 

lO 

_ — ... . 



4 

4 

4 

4       i 

tan  0 


•  .Utcr    lli.U(.' 


I  'i.igiiii.ll    . 


74      1       7i 


V  3*      ,        V 


7 

7 

<) 

9 

10 

10 

r 

o 


f 


.u 


l'"-l  ri'Iiruiiji       V 


-'i 


I'nst  (DiHk  r     V 


it    i  ~~k 


V     '       i 


-4 


s«t  ». 


1 

¥     !       a 


I        o         !  To  the  .'♦tre**  ..n 

i' -^  ■— -     ^    each  post  mu^^^ 
be  .uiileil  JJ", 


i 


STRESSES    IN    SI 


w    =  panel  live  load  on  one  truss, 
U\  =  panel  dcail  load  on  one  truss, 
Jf"=upiKM-  panel  dead  load  on  one  truss, 
0      =  inclination  of  diagonal  to  vertical. 


1 

3  Panel. 

■ 
4  Panel. 

i 

5 

Member. 

70 
- 

1 

„  i 

7V 

2 

70 

Tup  Chord    ....     I 

I 

2 

3 

t»              i*                  ,             .      2 

.1 

'•       ....    3 

(t                  ti                                                  1 

1 

•i 

r.'itt.uu  Chord    ...     I 

i 

i            • 

I 

t 

It             It                       <> 

1 

1            1 

I 

>i 

1       -, 
1      ,  " 

"      •    ■    ■    3 

i 

1 

"            "       ...    4 

It                      li                      ,        .         C 

I'.attcr  IW.uf  .     .     .     . 

f 

I 

S 

'i 

'^ 

1     Diagonal    ......     I 

i 

0 

1 

i 

4.                                                                            t 

1 

3 

i 

4 

5 

-- 

1 

6 

I'(jst  ('I'liriuiglil'.iidKc)    1 

i 

i! 

.i             (.            i.           1 

"     .    3 

i 

t 

l'.»t  (Dcck-Hridnc)     .     i 

-»- 

1     - 

ti            tt              t.                      2 

i_  _^ 

.1            t.               It                       , 

i 

1 

1 

!■ 

TABLE   XLI. 

STRESSES    IN    SINGLE-INTERSECTION    TRUSSES. 


I  on  one  truss, 
d  on  one  truss, 
cad  load  on  one  truss, 
diaironal  to  vertical. 


anel. 

4  Panel.        \ 

5  Panel. 

1 

6  Panel. 

7  Panel. 

. 7T 

8  Panel.          i 

9  Panel. 

Multiply  by 

;F. 

w 

...  ^ 

Wx        i 

2 

w 

3 

w 

f^'. 

IV 

s 

6 

u< 

n\ 

7t; 

1 

, 

2 

3 

4 

4 

5 

6 

6 

7 
9 

10 
10 

4 
4 

7       ij 

tanff 



3 

3 

4i 

4i 

6 

:i     ;     7i 

9 

— . ,  j 

6 

6 

8 

s 

10 

Ti 

2 

^4 

4 
4 

10         , 

I 
I 

-> 

3 

3 

74      1      74 

i 

4      1! 

- 

i 
4 

li 

- 

2 

3 

3 
5 
6 

3 

3 

4 

5 
6 

7 
9 

7       i 

— ; 

--^--1 

! 

1 

i 

1! 

10 

10 

4    !: 

■  1 

— — 

I 

'J 

2 

O 
—  I 

^ 

2i 

1 

¥■ 

3 

!     ¥      1      3i 

i    ¥ 

' 

_         i ; 

0 

¥ 

« 

2 

I 

0 
—  1 

¥     i      J     I 

--  --1 ■ 

k 

¥ 

4 

^ 
i^"^ 

t 

!       ■         1 



1 

» 

1     i    -^ 

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2 

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¥ 
¥ 

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2 

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o 

~j   -    - 

\    V          i 

II             \  'A                            i-\           \ 

i 

1 

1 

1 

f 


\ 


J  /SSES. 


13  Panel. 


w 


11 


l5 


W 


W 


v/- 


14  Panel. 


w 


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1 1.' 

13 


;  1  r 

13 


15  Panel. 


mJ 

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STRESSES    IN    D 


;i>    —  panel  live  luad  n\\  oik-  truss, 
//',  ~  panel  tleail   Unvd  on  one  truss, 
/r'^iijiper  panel  dead  load  on  one  tiuss, 
u     =  inclination  of  short  diagonal  in  \iriu'al, 
13     =  inclination  of  Ion;;  diaj^niuil  to  VLilual. 


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TABLE    XLII. 

STRESSES    IN    DOUBLE-INTERSECTION    TRUSSES. 


truss, 
'  truss, 

(Ml     (MR-    tlllSS, 

.  (lual   t(p  \riii(.';il, 

,oU.il    t(l    Vl'llUcll. 


■J     f 


i 


1\ 


lM;il(«I. 


< 


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^ 


DOUBLE  INTER 
WROUGHT  IRON  HlC 


->  f  i  ■ 


vv ;;? 


.  ;:? 


;■  ■iff" 


,H- 


DOUBLE  INTERSECTION 
DUGHT  IRON  HIGHWAY  BRIDGE 


lMiit(»I. 


X 


^* 


♦J 


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.y 


^i^:y^'-':^  ".ell 


HO' 


,11""' 


"'* 


.1!'"^ 


I. 


I 


\ 


¥<>. 


h-u,  I 


IM.ilo  II 


i-tn.i 


„,,,'/,;-.,,. 


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^ 

^ 

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1 

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f 

HJ 

u. 

II 


I 


GENERAL  DESCRI 


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1    .)-.  .-..itltiiiU^SiUi 


GENERAL  DESCRIPTIVE   PLATE    OF  DETAILS 


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IRON  HIG 


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_J_J_J__J,'J! 

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O   J 


"q"  o  o  o   j\->  J  o  Q  !_ j; 


o 


DET/^ILS   FOR  A  PONY  TRUSS 
IRON  HIGHWAY   BRIDGE. 


PlaU'IU. 


^■r'..-'^—-^- 


\ 


O  O  O    y  -» .  J    ■>  S~>,O...J: 


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DKTAILS   fohA  SINGLI:  LVI 

WIIH       SI  1)1'] 


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H  ~  ^  :^  -+-  :'^  Sf] 


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SINCJLi:  IXTKHSKCTIOX  HHIIX;!: 
nil     SIDi:     WALKS. 


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1 


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7'okiri       /hiK/lllill 

■/ri/liifi/l/    /ooJ. 


.:%^ 


I'Uih'V 

RIES  At 

'A 

■laGHWAY 

CU    A. 

Wl 

1 

I • 


DIAGRAM  OF    STRESSES 


POR     A 


160'    SPAN   IRON  HIGHW 
CLA.SS    A. 


^v 


?  /O"   J  IS'       JOSOv," 
Total,>r.     U  41  fj' 


/   •%•</,",' 7'/.      .?  .0/  a^ 
T()t(,/Srr       /7  25  n' 


,"  /f>"  ?4/s'r 

7hMSpr. 


U.4!fn  ■' 
.?..0/ '  i» 


77./I4.S.H.    on:.'    ■■ 

4      '-  J'v     6\)2  ;• 


4G4S'!,S.h'.     .O.J 

4  ••>■'   .v-'^'     //.;/; 


7x./a;'X.h'.     //.(>:' 
/;>//^r/  .Vr.    //.  /:' '? 


—  — •  Z7/Jr>4  ^ — 

S/xin 

nrrir  It'cfif/iiiiv 
lit  mi  l.piKilh 
Dr/tf/i  of  Trit.y 
hire  1.11(1(1 
Dcdil  1,(1(1  tl 
Wind  I'lTS-Vd" 


S/l  OF    STRESSES  AND    SECTIONS 


PliUrV. 


POR     A 


O'    SPAN   IRON  HIGHWAY  BRIDGE. 
CLASS    A. 


^^. 


/jY  /4.4!)n' 
S'er.  /S. 40  n" 
/8.40\\ 


.kj 


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;v " 

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ll?Ofjn/}. 

DpoiI  1.(1(1(1 

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Wind  I'lrs-siirr 

Jrr    s(//'/ 

/  '■///  l.(fl.  Hod. 


S^KU'Ht^f    -^  'i'^ 


■1 


O     O     <>     C     I 


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.   1  .•).>r,j, . 


I'UiUA'l 


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Mill  lliilr) 


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f-'itrnntWft  ^ 


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fif>'htu,f,ln 
J  ' tit* Hill 


>':vi  ■ 


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Vr^  >?•».; 


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>      /•  J'. 


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S  4 


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1-1     r\     O     O     O     O-  O     O-  O-  '>-  0--0 


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V ,    tf^»  h'ninw  like  fhi.f.  '/ittt  rtfjfit.'i  ami  fwt'  */>.*■ 


fhpfiat 


?     o     t. 


p^^., 


:k 


PORTION 
OF    A 

WORKING    DRAWING 

FOR    A    160  FT.  SPAN 

mON  HIGHWAY   BRIDGE 


\  'H  <C^<^  \  X    X 


■'■*'■'''"'  ■     -X       .      i   i      ,!    n    |i    ii     .  ! 


\nm'nl^rfiiii"f 


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jr«h,itf.i"„;,ii„ 


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/-^  .v.r  -f 


llia.'iffir  .-; 


■.X.'-   - 


k'-rlrrmf/fniil''  4!Ur'-'1<-<n-u-i 


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(•tntut '.'»■»* 

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FALSE  WORK. 

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